FILED PURSUANT TO RULE 424(b)(2)
                                                     REGISTRATION NO. 333-100641

PROSPECTUS SUPPLEMENT
(To prospectus dated December 11, 2002)
 
                                  $500,000,000
 
                               MASCO CORPORATION
 
                              4.80% NOTES DUE 2015
 
                             ----------------------
 
       The notes bear interest at the rate of 4.80% per year. Interest on the
notes is payable on June 15 and December 15 of each year, beginning December 15,
2005. The notes will mature on June 15, 2015. We may, at our option, redeem the
notes, in whole or in part, prior to maturity at the redemption price described
in this prospectus supplement.
 
       The notes are unsecured and rank equally with all of our other unsecured
senior indebtedness. The notes will be issued only in registered form in
denominations of $1,000 and integral multiples of $1,000.
 
                             ----------------------
 


                                                       PER NOTE                  TOTAL
                                                       --------                  -----
                                                                       
Public Offering Price(1)...........................        99.481%            $497,405,000
Underwriting Discount..............................         0.650%              $3,250,000
Proceeds, before expenses to Masco.................        98.831%            $494,155,000

 
---------------
 
(1) Plus accrued interest from June 10, 2005, if settlement occurs after that
    date.
 
       Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or determined if this
prospectus is truthful or complete. Any representation to the contrary is a
criminal offense.
 
       The notes will be ready for delivery in book-entry form only through The
Depository Trust Company, on or about June 10, 2005.
 
                             ----------------------
 
MERRILL LYNCH & CO.
                                   CITIGROUP
                                                                        JPMORGAN
 
                             ----------------------
 
             The date of this prospectus supplement is June 7, 2005

 
                               TABLE OF CONTENTS
 


                                                              PAGE
                                                              ----
                                                           
                      PROSPECTUS SUPPLEMENT
Ratio of Earnings to Fixed Charges..........................  S-3
Use of Proceeds.............................................  S-3
Description of Notes........................................  S-3
Underwriting................................................  S-7
 
                            PROSPECTUS
About This Prospectus.......................................    2
Special Note Regarding Forward-Looking Statements...........    2
Masco Corporation...........................................    3
Risk Factors................................................    3
Use of Proceeds.............................................    5
Ratio of Earnings to Fixed Charges..........................    5
Description of Debt Securities..............................    6
Description of Capital Stock................................   15
Description of Depositary Shares............................   17
Description of Share Purchase Contracts and Share Purchase
  Units.....................................................   20
Plan of Distribution........................................   20
Legal Opinions..............................................   21
Experts.....................................................   21
Where You Can Find More Information.........................   21

 
     You should rely only on the information contained or incorporated by
reference in this prospectus. We have not, and the underwriters have not,
authorized any other person to provide you with different information. If anyone
provides you with different or inconsistent information, you should not rely on
it. We are not, and the underwriters are not, making an offer to sell these
securities in any jurisdiction where the offer or sale is not permitted.
 
     THE TERMS "MASCO," "WE," "US," AND "OUR" REFER TO MASCO CORPORATION. OUR
EXECUTIVE OFFICES ARE LOCATED AT 21001 VAN BORN ROAD, TAYLOR, MICHIGAN 48180,
AND OUR TELEPHONE NUMBER IS (313) 274-7400.
 
                                       S-2

 
                       RATIO OF EARNINGS TO FIXED CHARGES
 
     Our ratios of earnings to fixed charges for the years ended December 31,
2000 through 2004 and the three months ended March 31, 2005 are set forth in the
table below.
 


                                           THREE MONTHS
                                              ENDED           YEAR ENDED DECEMBER 31,
                                            MARCH 31,     --------------------------------
                                               2005       2004   2003   2002   2001   2000
                                           ------------   ----   ----   ----   ----   ----
                                                                    
Ratio of earnings to fixed charges(1)....      5.6        7.0    5.3    4.6    2.0    4.7

 
---------------
 
(1) Ratio of earnings to fixed charges means the ratio of income before income
    taxes, extraordinary income and fixed charges to fixed charges, where fixed
    charges are the aggregate of interest expense, including amortization of
    debt expense and the estimated interest factor for rentals. Years prior to
    2002 have not been adjusted to exclude goodwill amortization expense.
 
                                USE OF PROCEEDS
 
     The net proceeds received by us from the sale of the notes offered hereby,
estimated at approximately $494 million, are expected to be applied to repay a
portion of our 6.75% notes due 2006. Prior to repayment of such indebtedness,
the net proceeds may be used for short-term investments.
 
                              DESCRIPTION OF NOTES
 
GENERAL
 
     The notes offered hereby will initially be limited to $500 million
aggregate principal amount. The notes are to be issued under an indenture, which
is more fully described in the accompanying prospectus.
 
     The notes will bear interest from June 10, 2005, payable semi-annually on
each June 15 and December 15, beginning on December 15, 2005, to the persons in
whose names the notes are registered at the close of business on the June 1 and
December 1, as the case may be, immediately preceding such June 15 and December
15. The notes will mature on June 15, 2015 and are not subject to any sinking
fund.
 
     We may, without the consent of the existing holders of the notes, issue
additional notes having the same terms so that in either case the existing notes
and the new notes form a single series under the indenture.
 
REDEMPTION AT OUR OPTION
 
     We may, at our option, redeem the notes in whole or in part at any time at
a redemption price equal to the greater of:
 
     - 100% of the principal amount of the notes to be redeemed, plus accrued
       interest to the redemption date, and
 
     - as determined by the Independent Investment Banker, the sum of the
       present values of the principal amount of and remaining scheduled
       payments of interest on the notes to be redeemed (not including any
       portion of payments of interest accrued as of the redemption date)
       discounted to the redemption date on a semi-annual basis at the Treasury
       Rate plus 15 basis points plus accrued interest to the redemption date
       for the notes.
 
     The redemption price will be calculated assuming a 360-day year consisting
of twelve 30-day months.
 
     "Treasury Rate" means, with respect to any redemption date, the rate per
year equal to the semiannual equivalent yield to maturity of the Comparable
Treasury Issue, calculated on the third business day preceding
 
                                       S-3

 
the redemption date, assuming a price for the Comparable Treasury Issue
(expressed as a percentage of its principal amount) equal to the Comparable
Treasury Price for that redemption date.
 
     "Comparable Treasury Issue" means the United States Treasury security
selected by the Independent Investment Banker as having a maturity comparable to
the remaining term of the notes that would be used, at the time of selection and
in accordance with customary financial practice, in pricing new issues of
corporate debt securities of comparable maturity to the remaining term of the
notes.
 
     "Comparable Treasury Price" means, with respect to any redemption date:
 
     - the average of the Reference Treasury Dealer Quotations for that
       redemption date, after excluding the highest and lowest of the Reference
       Treasury Dealer Quotations, or
 
     - if the trustee obtains fewer than three Reference Treasury Dealer
       Quotations, the average of all Reference Treasury Dealer Quotations so
       received.
 
     "Independent Investment Banker" means one of the Reference Treasury Dealers
appointed by the trustee after consultation with us.
 
     "Reference Treasury Dealer" means (a) each of Merrill Lynch, Pierce, Fenner
& Smith Incorporated and Citigroup Global Markets Inc. and their respective
successors, unless either of them ceases to be a primary U.S. Government
securities dealer in New York City (a "Primary Treasury Dealer"), in which case
we shall substitute another Primary Treasury Dealer, and (b) any other Primary
Treasury Dealer selected by us.
 
     "Reference Treasury Dealer Quotations" means, with respect to each
Reference Treasury Dealer and any redemption date, the average, as determined by
the trustee, of the bid and asked prices for the Comparable Treasury Issue
(expressed in each case as a percentage of its principal amount) quoted in
writing to the trustee by that Reference Treasury Dealer at 5:00 p.m., New York
City time, on the third business day preceding that redemption date.
 
     We will mail notice of any redemption at least 30 days but not more than 60
days before the redemption date to each holder of the notes to be redeemed.
 
     Unless we default in payment of the redemption price, on and after the
redemption date, interest will cease to accrue on the notes or portions of the
notes called for redemption.
 
BOOK-ENTRY SYSTEM
 
     The notes will be issued in fully registered form in the name of Cede &
Co., as nominee of The Depository Trust Company ("DTC"). For each series of
notes, one or more fully registered certificates will be issued as global notes
in the aggregate principal amount of the notes of such series. Such global notes
will be deposited with DTC and may not be transferred except as a whole by DTC
to a nominee of DTC or by a nominee of DTC to DTC or another nominee of DTC or
by DTC or any nominee to a successor of DTC or a nominee of such successor.
 
     So long as DTC, or its nominee, is the registered owner of a global note,
DTC or such nominee, as the case may be, will be considered the sole owner or
holder of the notes represented by such global note for all purposes under the
indenture. Except as set forth below, owners of beneficial interests in a global
note will not be entitled to have the notes represented by such global note
registered in their names, will not receive or be entitled to receive physical
delivery of such notes in definitive form and will not be considered the owners
or holders thereof under the indenture. Accordingly, each person owning a
beneficial interest in a global note must rely on the procedures of DTC for such
global note and, if such person is not a participant in DTC (as described
below), on the procedures of the participant through which such person owns its
interest, to exercise any rights of a holder under the indenture.
 
                                       S-4

 
     DTC has advised Masco and the underwriters as follows:
 
     DTC is a limited-purpose trust company organized under the New York Banking
Law, a "banking organization" under the New York Banking Law, a member of the
Federal Reserve System, a "clearing corporation" within the meaning of the New
York Uniform Commercial Code, and a "clearing agency" registered pursuant to the
provisions of Section 17A of the Securities Exchange Act of 1934, as amended.
DTC holds securities that its participants deposit with DTC. DTC also
facilitates the settlement among participants of securities transactions, such
as transfers and pledges in deposited securities, through electronic
computerized book-entry changes in participants' accounts, thereby eliminating
the need for physical movement of securities certificates. Direct participants
include securities brokers and dealers, banks, trust companies, clearing
corporations, and certain other organizations. DTC is owned by a number of its
direct participants and by the New York Stock Exchange, Inc., the American Stock
Exchange, Inc. and the National Association of Securities Dealers, Inc. Access
to the DTC system is also available to others such as securities brokers and
dealers, banks, and trust companies that clear through or maintain a custodial
relationship with a direct participant, either directly or indirectly. The rules
applicable to DTC and its participants are on file with the Securities and
Exchange Commission.
 
     Purchases of notes under the DTC system must be made by or through direct
participants, which will receive a credit for the notes on DTC's records. The
ownership interest of each actual purchaser, or beneficial owner, of notes is in
turn to be recorded on the direct and indirect participant's records. Beneficial
owners will not receive written confirmation from DTC of their purchase, but
beneficial owners are expected to receive written confirmations providing
details of the transaction, as well as periodic statements of their holdings,
from the direct and indirect participant through which the beneficial owner
entered into the transaction. Transfers of ownership interests in the notes are
to be accomplished by entries made on the books of participants acting on behalf
of beneficial owners. Beneficial owners will not receive certificates
representing their ownership interests in the notes, except in the event that
use of the book-entry system for the notes is discontinued.
 
     To facilitate subsequent transfers, all notes deposited by participants
with DTC are registered in the name of DTC's partnership nominee, Cede & Co. The
deposit of notes with DTC and their registration in the name of Cede & Co.
effect no change in beneficial ownership. DTC has no knowledge of the actual
beneficial owners of the notes; DTC's records reflect only the identity of the
direct participants to whose accounts such notes are credited, which may or may
not be the beneficial owners. The participants will remain responsible for
keeping account of their holdings on behalf of their customers.
 
     Conveyance of notices and other communications by DTC to direct
participants, by direct participants to indirect participants, and by direct
participants and indirect participants to beneficial owners will be governed by
arrangements among them, subject to any statutory or regulatory requirements as
may be in effect from time to time.
 
     Neither DTC nor Cede & Co. will consent or vote with respect to the global
notes. Under its usual procedures DTC mails an Omnibus Proxy to the issuer as
soon as possible after the record date. The Omnibus Proxy assigns Cede & Co.'s
consenting or voting rights to those direct participants to whose accounts the
notes are credited on the record date (identified in the listing attached to the
Omnibus Proxy).
 
     Principal and interest payments on the global notes will be made to DTC.
Masco expects that DTC, upon receipt of any payment of principal or interest in
respect of a global note, will credit immediately participants' accounts with
payments in amounts proportionate to their respective beneficial interests in
the principal amount of such global note as shown on DTC's records. Masco also
expects that payments by participants to beneficial owners will be governed by
standing instructions and customary practices, as is the case with securities
held for the accounts of customers in bearer form or registered in "street
name", and will be the responsibility of such participant and not of DTC, Masco
or the trustee, subject to any statutory or regulatory requirements as may be in
effect from time to time.
 
     DTC may discontinue providing its service as securities depositary with
respect to the notes at any time by giving reasonable notice to Masco or the
trustee. In addition, Masco may decide to discontinue use of the system of
book-entry transfers through DTC (or a successor securities depositary). Under
such
 
                                       S-5

 
circumstances, if a successor securities depositary is not obtained, note
certificates in fully registered form are required to be printed and delivered
to beneficial owners of the global notes representing such notes.
 
     The information in this section concerning DTC and DTC's book-entry system
has been obtained from sources that Masco believes to be reliable (including
DTC), but Masco takes no responsibility for the accuracy thereof.
 
     Neither Masco, the trustee nor the underwriters will have any
responsibility or obligation to participants, or the persons for whom they act
as nominees, with respect to the accuracy of the records of DTC, its nominee or
any participant with respect to any ownership interest in the notes or payments
to, or the providing of notice to participants or beneficial owners.
 
     The notes will trade in DTC's Same-Day Funds Settlement System and
secondary market trading activity in the notes will, therefore, settle in
immediately available funds. All applicable payments of principal and interest
on the notes issued as global notes will be made by Masco in immediately
available funds.
 
     For other terms of the notes, see "Description of Debt Securities" in the
accompanying prospectus.
 
DEFEASANCE
 
     The notes will be subject to defeasance and discharge and to defeasance of
certain covenants as set forth in the indenture, see "Description of Debt
Securities -- Defeasance" in the prospectus.
 
                                       S-6

 
                                  UNDERWRITING
 
     Subject to the terms and conditions set forth in the underwriting
agreement, we have agreed to sell to each of the underwriters named below, and
each of the underwriters has severally agreed to purchase, the principal amount
of notes set forth opposite its name.
 


                                                                PRINCIPAL
UNDERWRITERS                                                      AMOUNT
------------                                                    ---------
                                                            
Merrill Lynch, Pierce, Fenner & Smith
Incorporated................................................   $200,000,000
Citigroup Global Markets Inc. ..............................    150,000,000
J.P. Morgan Securities Inc..................................    150,000,000
                                                               ------------
Total.......................................................   $500,000,000
                                                               ============

 
     The underwriters have agreed to purchase all of the notes sold pursuant to
the underwriting agreement if any of these notes are purchased. If an
underwriter defaults, the underwriting agreement provides that, under certain
circumstances, the purchase commitments of the nondefaulting underwriters may be
increased or the underwriting agreement may be terminated.
 
     We have been advised by the underwriters that they propose to offer part of
the notes purchased by them directly to the public at the public offering price
set forth on the cover page of this prospectus supplement, and may offer part of
the notes to certain dealers at that price less a concession not in excess of
0.40% of the principal amount of the notes. The underwriters may allow and the
dealers may reallow a concession not in excess of 0.25% of the principal amount
of the notes to certain other dealers. After the initial public offering, the
underwriters may change the public offering price and other selling terms.
 
     In the ordinary course of their respective businesses, certain of the
underwriters or their affiliates perform investment banking, commercial banking
and other financial service transactions for us and our affiliates, including
acting as lenders under various loan facilities.
 
     Richard A. Manoogian, Chairman and Chief Executive Officer of Masco, is a
director of JPMorgan Chase & Co.
 
     J.P. Morgan Trust Company, National Association, which acts as trustee
under the indenture, is an affiliate of JPMorgan Chase & Co. and J.P. Morgan
Securities Inc., one of the underwriters.
 
     The underwriting agreement provides that we will indemnify the underwriters
against certain liabilities, including liabilities under the Securities Act of
1933.
 
     We have agreed not to offer or sell or otherwise dispose of for cash
without the consent of the underwriters any debt securities of Masco
substantially similar to the notes until the date following the date on which we
deliver the notes to the underwriters.
 
     We do not expect to list the notes on any securities exchange. The
underwriters may from time to time purchase and sell notes in the secondary
market, but are not obligated to do so, and there can be no assurance that there
will be a secondary market for the notes or liquidity in the secondary market if
one develops.
 
     We estimate that we will spend approximately $75,000 for printing, trustee
and legal fees and other expenses related to this offering.
 
     The underwriters are permitted to engage in certain transactions that
stabilize the price of the notes. Such transactions consist of bids or purchases
for the purpose of pegging, fixing or maintaining the price of the notes. If the
underwriters create a short position in the notes in connection with the
offering, i.e., if they sell notes in an aggregate principal amount exceeding
that set forth on the cover page of this prospectus supplement, the underwriters
may reduce that short position by purchasing notes in the open market. In
 
                                       S-7

 
general, purchases of a security for the purpose of stabilization or to reduce a
short position could cause the price of the security to be higher than it might
be in the absence of such purchases.
 
     Neither we nor the underwriters make any representation or prediction as to
the direction or magnitude of any effect that the transactions described above
may have on the price of the notes. In addition, neither we nor the underwriters
make any representation that the underwriters will engage in such transactions
or that such transactions, once commenced, will not be discontinued without
notice.
 
                                       S-8

 
                                 $2,000,000,000
                               MASCO CORPORATION
 
                                Debt Securities
                         Preferred Stock ($1 Par Value)
                          Common Stock ($1 Par Value)
                            Share Purchase Contracts
                              Share Purchase Units
 
                             ----------------------
 
     We may offer and issue debt securities and shares of our preferred stock
and common stock from time to time. The debt securities and shares of preferred
stock may be convertible into or exchangeable for shares of our common stock or
other securities. We may offer and issue preferred stock either directly or
represented by depositary shares. We may offer contracts to purchase our common
stock from time to time either separately or as part of a unit along with our
debt securities or preferred stock or debt obligations of third parties. This
prospectus describes the general terms of these securities and the general
manner in which we will offer them. We will provide the specific terms of these
securities in supplements to this prospectus. The prospectus supplements will
also describe the specific manner in which we will offer these securities.
 
     Our common stock is listed on the New York Stock Exchange under the symbol
"MAS." On December 10, 2002, the closing price of our common stock was $19.77
per share.
 
                             ----------------------
 
     INVESTING IN THESE SECURITIES INVOLVES RISKS.  SEE "RISK FACTORS" BEGINNING
ON PAGE 3.
 
                             ----------------------
 
     NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES, OR DETERMINED IF
THIS PROSPECTUS IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.
 
                             ----------------------
 
     We may offer these securities in amounts, at prices and on terms determined
at the time of offering. We may sell the securities directly to you, through
agents we select, or through underwriters and dealers we select. If we use
agents, underwriters or dealers to sell these securities, we will name them and
describe their compensation in a prospectus supplement.
 
                             ----------------------
 
               The date of this prospectus is December 11, 2002.

 
                              -------------------
 
                               TABLE OF CONTENTS
                              -------------------
 


                          CAPTION                               PAGE
                          -------                               ----
                                                             
About This Prospectus.......................................      2
Special Note Regarding Forward-Looking Statements...........      2
Masco Corporation...........................................      3
Risk Factors................................................      3
Use of Proceeds.............................................      5
Ratio of Earnings to Combined Fixed Charges and Preferred
  Stock Dividends...........................................      5
Description of Debt Securities..............................      6
Description of Capital Stock................................     15
Description of Depositary Shares............................     17
Description of Share Purchase Contracts and Share Purchase
  Units.....................................................     20
Plan of Distribution........................................     20
Legal Opinions..............................................     21
Experts.....................................................     21
Where You Can Find More Information.........................     21

 
                             ABOUT THIS PROSPECTUS
 
     This prospectus is part of a registration statement that we filed with the
Securities and Exchange Commission, referred to as the SEC in this prospectus,
utilizing a shelf registration process. Under this shelf process, we may issue,
from time to time, up to $2,000,000,000 of debt securities, shares of our
preferred stock and common stock, and share purchase contracts and related share
purchase units. Each time we issue securities under the registration statement
we will provide a prospectus supplement that will contain specific information
about the terms of that offering. The prospectus supplement may also add, update
or change information contained in this prospectus. You should read both this
prospectus and any prospectus supplement together with the additional
information described under the heading "Where You Can Find More Information."
 
               SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS
 
     In this prospectus and in the documents we incorporate by reference, we
state our views about our future performance. These views, which constitute
"forward-looking statements" under the Private Securities Litigation Reform Act
of 1995, involve risks and uncertainties that are difficult to predict and,
accordingly, our actual results may differ materially from the results discussed
in such forward-looking statements. The Company has no obligation to update any
forward-looking statements as a result of new information, future events or
otherwise.
 
     Factors that affect our results of operations include the levels of home
improvement and residential construction activity principally in North America
and Europe (including repair and remodeling and new construction), our ability
to effectively manage our overall cost structure, fluctuations in European
currencies (primarily the euro and British pound), the importance of and our
relationships with home centers (including The Home Depot, which represented
approximately 25 percent of our sales in 2001) as distributors of home
improvement and building products, and our ability to maintain our leadership
positions in our markets in the face of increasing global competition.
Historically, we have been able to largely offset cyclical declines in housing
markets through new product introductions and acquisitions as
 
                                        2

 
well as market share gains. Additional factors that may significantly affect our
performance are discussed under "Management's Discussion and Analysis of
Financial Condition and Results of Operations" in our Annual Report on Form 10-K
and in our Quarterly Reports on Form 10-Q that are on file with the SEC as well
as under the heading "Risk Factors" in this prospectus.
 
     YOU SHOULD RELY ONLY ON THE INFORMATION CONTAINED IN THIS PROSPECTUS, IN
THE ACCOMPANYING PROSPECTUS SUPPLEMENT AND IN MATERIAL WE FILE WITH THE SEC. WE
HAVE NOT AUTHORIZED ANYONE TO PROVIDE YOU WITH INFORMATION THAT IS DIFFERENT.
 
     WE ARE OFFERING TO SELL, AND SEEKING OFFERS TO BUY, THE SECURITIES
DESCRIBED IN THIS PROSPECTUS ONLY WHERE OFFERS AND SALES ARE PERMITTED. SINCE
INFORMATION THAT WE FILE WITH THE SEC IN THE FUTURE WILL AUTOMATICALLY UPDATE
AND SUPERSEDE INFORMATION CONTAINED IN THIS PROSPECTUS OR ANY ACCOMPANYING
PROSPECTUS SUPPLEMENT, YOU SHOULD NOT ASSUME THAT THE INFORMATION CONTAINED IN
THIS PROSPECTUS OR IN ANY PROSPECTUS SUPPLEMENT IS ACCURATE AS OF ANY DATE OTHER
THAN THE DATE ON THE FRONT OF THE DOCUMENT.
 
                               MASCO CORPORATION
 
     Masco Corporation manufactures, sells and installs home improvement and
building products, with emphasis on brand name products and services holding
leadership positions in their markets. Masco is among the largest manufacturers
in North America of brand name consumer products designed for the home
improvement and home construction markets. Our business segments are: cabinets
and related products; plumbing products; installation and other services;
decorative architectural products; and other specialty products.
 
     Our executive offices are located at 21001 Van Born Road, Taylor, Michigan
48180. Our telephone number is (313) 274-7400 and our website address is
http://www.masco.com. The information on our website is not a part of this
prospectus. Except as the context otherwise indicates, the terms "Masco," "we,"
"us," and "our" refer to Masco Corporation.
 
                                  RISK FACTORS
 
     Before purchasing these securities, you should consider all of the
information set forth in this prospectus, in any accompanying prospectus
supplement and the information incorporated by reference in this prospectus and,
in particular, you should take into account the risk factors set forth below.
 
WE CANNOT ASSURE YOU THAT OUR GROWTH STRATEGIES WILL BE SUCCESSFUL
 
     Mergers and acquisitions have historically contributed significantly to our
long-term growth, after the initial impact on earnings of transaction-related
costs and expenses such as interest and added depreciation and amortization.
Successful strategic acquisitions require the integration of operations and
management and other efforts to realize the benefits that may be available to us
following the acquisition. Although we believe that we have been successful in
doing so in the past, we can give no assurance that we will continue to be able
to identify, acquire and integrate successful strategic acquisitions in the
future or be able to implement successfully our operating and growth strategies
within our existing markets or with respect to any future product or geographic
diversification efforts.
 
                                        3

 
OUR BUSINESS HAS BEEN AFFECTED BY ECONOMIC WEAKNESS AND BUSINESS CONDITIONS
 
     Factors that affect our results of operations include the levels of home
improvement and residential construction activity, principally in North America
and Europe (including repair and remodeling and new construction), our ability
to effectively manage our overall cost structure, fluctuations in European
currencies (primarily the euro and British pound), and our ability to maintain
our leadership positions in our markets in the face of increasing global
competition. Historically, we have been able largely to offset cyclical declines
in housing markets through new product introductions and acquisitions as well as
market share gains. We can give no assurance that we will be able to offset
these cyclical declines in the future.
 
WE RELY ON OUR KEY CUSTOMERS
 
     Our relationships with home centers are important to us. Direct sales of
our product lines to home center retailers have increased substantially in
recent years and, in 2001, sales to our largest customer, The Home Depot, were
$2.1 billion (approximately 25 percent of total sales). Although builders,
dealers and other retailers represent other channels of distribution for our
products, we believe that the loss of a substantial portion of our sales to The
Home Depot would have a material adverse impact on our company.
 
WE ARE DEFENDANTS IN LITIGATION INVOLVING PRODUCTS OF OUR BEHR PROCESS
CORPORATION SUBSIDIARY.
 
     We and our Behr Process Corporation subsidiary are defendants in several
class action lawsuits, including a class action lawsuit in the State of
Washington against Behr. These lawsuits related to certain of Behr's previously
manufactured exterior wood coating products. None of the complaints set forth
any specific amount of damages.
 
     On October 29, 2002, we announced preliminary settlements to resolve all of
these class actions pending in the United States under which all claims relating
to the products would be dismissed without any admission of liability or
wrongdoing following final court approval of the settlements. Preliminary
settlement agreements have been reached; the aggregate cost of which we estimate
will be in a range of $166 million to $206 million. The Company has concluded
that no amount within that range is more likely than any other, and therefore
has recorded $166 million as a liability in the third quarter 2002 consolidated
financial statements related to these settlements. The Company is currently
negotiating its liability insurers' contribution to the cost of the settlements.
However, no insurance amounts have been recorded as of November 30, 2002.
Recoveries from liability insurers or other third parties will be recorded at
such time as they are agreed to, or otherwise received. Management believes that
the settlements described above will receive final approval without substantial
changes, although there can be no assurance in that regard. Management believes
that the Company will not incur additional material losses with regard to this
matter.
 
     These proceedings and any recent developments concerning this litigation
are more fully described in our periodic and other reports filed with the SEC
and incorporated by reference into the registration statement of which this
prospectus forms a part.
 
OUR INTERNATIONAL BUSINESS HAS SPECIAL RISKS
 
     Our international operations outside of North America, principally in
Europe, are subject to political, monetary, economic and other risks attendant
generally to international businesses. These risks generally vary from country
to country. Results of existing European operations have been adversely
influenced in recent years, in part due to softness in our European markets,
competitive pricing pressures on certain products, the effect of a higher
percentage of lower margin sales to total European sales and a stronger U.S.
dollar.
 
                                        4

 
OUR MARKETS ARE HIGHLY COMPETITIVE
 
     The major markets for our products are highly competitive. Competition in
all of our product lines is based primarily on performance, quality, style,
delivery, customer service and price, with the relative importance of such
factors varying among product categories.
 
WE HAVE FINANCIAL COMMITMENTS AND INVESTMENTS IN FINANCIAL ASSETS
 
     As part of our acquisition strategy we often structure acquisition and
other transactions to provide, in addition to the consideration paid at closing,
contingent consideration to be paid in cash or stock if specified conditions are
met. These conditions may include the operating performance of the acquired
business in the case of an acquisition, the price of our common stock, or both.
In addition to possibly increasing the consideration we ultimately pay for an
acquisition, these conditions may also affect the number of contingently
issuable shares that are included in our periodic computation of diluted
earnings per common share, the amount of our accrued liabilities and our results
of operations.
 
     We also maintain investments in a number of private equity funds and in
marketable securities. These investments are generally carried as long-term
assets on our balance sheet. We record investments in marketable securities at
fair value, which is subject to adjustment based on market fluctuations.
Unrealized losses that are temporary impairments and unrealized gains are
recognized, net of taxes, through shareholders' equity as a component of other
comprehensive income. Realized gains and losses and charges for other-
than-temporary impairments are included in other income.
 
     Our investments in private equity funds have no readily ascertainable
market value. These equity funds may invest in transactions that have an above
average degree of financial leverage or business risk. Our investments in these
funds are carried at cost and are periodically evaluated for impairment or when
circumstances indicate an impairment may exist. Income and gains, net realized
from these investments are included in other income when distributed or
received. In addition, we have commitments that may require us to contribute
additional capital to these private equity funds.
 
                                USE OF PROCEEDS
 
     We expect to use substantially all of the net proceeds from sales of the
securities described in this prospectus for our general corporate purposes,
which may include making additions to our working capital, repaying
indebtedness, financing acquisitions and investments in new or existing lines of
business. We will describe our intended use of the proceeds from a particular
offering of securities in the related prospectus supplement. Funds not required
immediately for any of the previously listed purposes may be invested in
marketable securities.
 
                  RATIO OF EARNINGS TO COMBINED FIXED CHARGES
                         AND PREFERRED STOCK DIVIDENDS
 
     Our ratios of earnings to combined fixed charges and preferred stock
dividends were as follows:
 


                         YEAR ENDED DECEMBER 31,
NINE MONTHS ENDED    --------------------------------
SEPTEMBER 30, 2002   2001   2000   1999   1998   1997
------------------   ----   ----   ----   ----   ----
                                  
       4.5           2.0    4.9    7.0    7.6    7.5

 
     We calculated these ratios by dividing earnings before income taxes,
extraordinary income and fixed charges by our fixed charges and preferred stock
dividends.
 
     We included in the ratios the earnings and combined fixed charges and
preferred stock dividends of Masco and its consolidated subsidiaries and the
dividends received from 50% or less owned companies less our equity in their
undistributed earnings. Fixed charges consist of
 
                                        5

 
interest, amortization of debt expense and the portion of rentals for real and
personal properties that we deem representative of the interest factor.
 
     Excluding the third quarter 2002 pre-tax charge for litigation settlement
of $166 million, a third quarter 2001 pre-tax non-cash charge of $530 million
and a fourth quarter 2000 pre-tax non-cash charge of $145 million, the ratio of
earnings to combined fixed charges and preferred stock dividends would have been
5.3 for the nine months ended September 30, 2002 and 3.9 and 5.6 for 2001 and
2000, respectively.
 
                         DESCRIPTION OF DEBT SECURITIES
 
DEBT MAY BE SENIOR OR SUBORDINATED
 
     We may issue senior or subordinated debt securities. The senior debt
securities will constitute part of our senior debt, will be issued under our
Senior Debt Indenture, as defined below, and will rank on a parity with all of
our other unsecured and unsubordinated debt. The subordinated debt securities
will be issued under our Subordinated Debt Indenture, as defined below, and will
be subordinate and junior in right of payment, as set forth in the Subordinated
Debt Indenture, to all of our "senior indebtedness," which is defined in our
Subordinated Debt Indenture. If this prospectus is being delivered in connection
with a series of subordinated debt securities, the accompanying prospectus
supplement or the information we incorporate in this prospectus by reference
will indicate the approximate amount of senior indebtedness outstanding as of
the end of the most recent fiscal quarter. We refer to our Senior Debt Indenture
and our Subordinated Debt Indenture individually as an "indenture" and
collectively as the "indentures."
 
     We have summarized below the material provisions of the indentures and the
debt securities, or indicated which material provisions will be described in the
related prospectus supplement. These descriptions are only summaries, and each
investor should refer to the applicable indenture, which describes completely
the terms and definitions summarized below and contains additional information
regarding the debt securities.
 
     Any reference to particular sections or defined terms of the applicable
indenture in any statement under this heading qualifies the entire statement and
incorporates by reference the applicable section or definition into that
statement. The indentures are substantially identical, except for the provisions
relating to our negative pledge and limitations on sales and leasebacks, which
are included in the Senior Debt Indenture only, and the provisions relating to
subordination, which are included in the Subordinated Debt Indenture only.
Neither indenture limits our ability to incur additional indebtedness.
 
     We may issue debt securities from time to time in one or more series. The
debt securities may be denominated and payable in U.S. dollars or foreign
currencies. We may also issue debt securities, from time to time, with the
principal amount or interest payable on any relevant payment date to be
determined by reference to one or more currency exchange rates, securities or
baskets of securities, commodity prices or indices. Holders of these types of
debt securities will receive payments of principal or interest that depend upon
the value of the applicable currency, security or basket of securities,
commodity or index on or shortly before the relevant payment dates. As a result,
you may receive a payment of principal on any principal payment date, or a
payment of interest on any interest payment date, that is greater than or less
than the amount of principal or interest otherwise payable on such dates,
depending upon the value on such dates of the applicable currency, security or
basket of securities, commodity or index. Information as to the methods for
determining the amount of principal or interest payable on any date, the
currencies, securities or baskets of securities, commodities or indices to which
the amount payable on such date is linked and any
 
                                        6

 
additional material United States federal income tax considerations will be set
forth in the applicable prospectus supplement.
 
     Debt securities may bear interest at a fixed rate, which may be zero, or a
floating rate. Debt securities bearing no interest or interest at a rate that at
the time of issuance is below the prevailing market rate may be sold at a
discount below their stated principal amount.
 
     We may, without the consent of the existing holders of any series of debt
securities, issue additional debt securities having the same terms so that the
existing debt securities and the new debt securities form a single series under
the indenture.
 
TERMS SPECIFIED IN PROSPECTUS SUPPLEMENT
 
     The prospectus supplement will contain, where applicable, the following
terms of and other information relating to any offered debt securities:
 
- classification as senior or subordinated debt securities and the specific
  designation of such securities;
 
- aggregate principal amount and purchase price;
 
- currency in which the debt securities are denominated and/or in which
  principal, and premium, if any, and/or interest, if any, is payable;
 
- minimum denominations;
 
- date of maturity;
 
- the interest rate or rates or the method by which a calculation agent will
  determine the interest rate or rates, if any;
 
- the interest payment dates, if any;
 
- any repayment, redemption, prepayment or sinking fund provisions, including
  any redemption notice provisions;
 
- whether we will issue the debt securities in definitive form or in the form of
  one or more global securities;
 
- the terms on which holders of the debt securities may convert or exchange
  these securities into our common stock or other securities of Masco or other
  entities;
 
- information as to the methods for determining the amount of principal or
  interest payable on any date and/or the currencies, securities or baskets of
  securities, commodities or indices to which the amount payable on that date is
  linked;
 
- any special United States federal income tax consequences applicable to the
  debt securities being issued;
 
- whether we will issue the debt securities by themselves or as part of a unit
  together with other securities; and
 
- any other specific terms of the debt securities, including any additional
  events of default or covenants, and any terms required by or advisable under
  applicable laws or regulations.
 
REGISTRATION AND TRANSFER OF DEBT SECURITIES
 
     You may present debt securities for exchange and transfer in the manner, at
the places and subject to the restrictions set forth in the applicable
indenture. We will provide you those services free of charge, although you may
have to pay any tax or other governmental charge payable in connection with any
exchange or transfer, as set forth in the applicable indenture.
 
     If any of the debt securities are held in global form, the procedures for
transfer of interests in those securities will depend upon the procedures of the
depositary for those global securities. See "Global Securities" below.
 
DEFEASANCE
 
     Unless the prospectus supplement states otherwise, we will be able to
discharge all of our obligations, other than administrative obligations such as
facilitating transfers and exchanges of certificates and replacement of lost or
mutilated certificates, relating to a series of
 
                                        7

 
debt securities under an indenture by depositing cash and/or U.S. Government
obligations with the trustee in an amount sufficient to make all of the
remaining payments of principal, premium and interest on those debt securities
when those payments are due. We can do this only if we have delivered to the
trustee, among other things, an opinion of counsel based on a United States
Internal Revenue Service ruling or other change in U.S. federal income tax law
stating that holders will not recognize any gain or loss for U.S. federal income
tax purposes as a result of this deposit.
 
     We can also avoid having to comply with the restrictive covenants in the
applicable indenture, such as the negative pledge and the limitation on sale and
leaseback transactions covenants in the Senior Debt Indenture, by depositing
cash and/or U.S. Government obligations with the trustee in an amount sufficient
to make all of the remaining payments of principal, premium and interest on the
outstanding debt securities when those payments are due. We can do this only if
we have delivered to the trustee, among other things, an opinion of counsel
stating that holders of those securities will not recognize any gain or loss for
U.S. federal income tax purposes as a result of this deposit.
 
INDENTURES
 
     Debt securities that will be senior debt will be issued under an Indenture
dated as of February 12, 2001 between Masco and Bank One Trust Company, National
Association, as trustee. We call that indenture, as further supplemented from
time to time, the Senior Debt Indenture. Debt securities that will be
subordinated debt will be issued under an Indenture between Masco and The Bank
of New York, as trustee. We call that indenture, as further supplemented from
time to time, the Subordinated Debt Indenture. We refer to Bank One Trust
Company, National Association and The Bank of New York individually as a
"trustee" and collectively as the "trustees."
 
SUBORDINATION PROVISIONS
 
     There are contractual provisions in the Subordinated Debt Indenture that
may prohibit us from making payments on our subordinated debt securities.
Subordinated debt securities are subordinate and junior in right of payment, to
the extent and in the manner stated in the Subordinated Debt Indenture, to all
of our senior indebtedness.
 
     The Subordinated Debt Indenture defines senior indebtedness generally as
obligations of, or guaranteed or assumed by, Masco for borrowed money or
evidenced by bonds, notes or debentures or other similar instruments or incurred
in connection with the acquisition of property, and amendments, renewals,
extensions, modifications and refundings of any of that indebtedness or of those
obligations. The subordinated debt securities and any other obligations
specifically designated as being subordinate in right of payment to senior
indebtedness are not senior indebtedness as defined under the Subordinated Debt
Indenture.
 
     The Subordinated Debt Indenture provides that, unless all principal of and
any premium or interest on the senior indebtedness has been paid in full, or
provision has been made to make those payments in full, no payment of principal
of, or any premium or interest on, any subordinated debt securities may be made
in the event:
 
- of any insolvency or bankruptcy proceedings, or any receivership, liquidation,
  reorganization or other similar proceedings involving us or a substantial part
  of our property;
 
- a default has occurred in the payment of principal, any premium, interest or
  other monetary amounts due and payable on any senior indebtedness, and that
  default has not been cured or waived or has not ceased to exist;
 
- there has occurred any other event of default with respect to senior
  indebtedness that permits the holder or holders of the senior indebtedness to
  accelerate the maturity of the senior indebtedness, and that event of default
 
                                        8

 
  has not been cured or waived or has not ceased to exist; or
 
- that the principal of and accrued interest on any subordinated debt securities
  have been declared due and payable upon an event of default as defined under
  the Subordinated Debt Indenture, and that declaration has not been rescinded
  and annulled as provided under the Subordinated Debt Indenture.
 
     If the trustee under the Subordinated Debt Indenture or any holders of the
subordinated debt securities receive any payment or distribution that is
prohibited under the subordination provisions, then the trustee or the holders
will have to repay that money to the holders of the senior indebtedness.
 
     Even if the subordination provisions prevent us from making any payment
when due on the subordinated debt securities of any series, we will be in
default on our obligations under that series if we do not make the payment when
due. This means that the trustee under the Subordinated Debt Indenture and the
holders of subordinated debt securities of that series can take action against
us, but they will not receive any money until the claims of the holders of
senior indebtedness have been fully satisfied.
 
COVENANTS RESTRICTING PLEDGES, MERGERS AND OTHER SIGNIFICANT CORPORATE ACTIONS
 
     In the following discussion, we use a number of capitalized terms which
have special meanings under the indentures. We provide definitions of these
terms under "Definitions" below.
 
     Negative Pledge. Section 10.04 of the Senior Debt Indenture provides that
so long as any of the senior debt securities remains outstanding, we will not,
nor will we permit any Consolidated Subsidiary to, issue, assume or guarantee
any Debt if such Debt is secured by a mortgage upon any Principal Property or
upon any shares of stock or indebtedness of any Consolidated Subsidiary which
owns or leases any Principal Property, whether such Principal Property is owned
on the date of the Senior Debt Indenture or is thereafter acquired, without in
any such case effectively providing that the senior debt securities shall be
secured equally and ratably with such Debt, except that the foregoing
restrictions shall not apply to:
 
- mortgages on property, shares of stock or indebtedness of any corporation
  existing at the time such corporation becomes a Consolidated Subsidiary;
 
- mortgages on property existing at the time of acquisition thereof, or to
  secure Debt incurred for the purpose of financing all or any part of the
  purchase price of such property, or to secure any Debt incurred prior to or
  within 120 days after the later of the acquisition, completion of construction
  or improvement or the commencement of commercial operation of such property,
  which Debt is incurred for the purpose of financing all or any part of the
  purchase price thereof or construction or improvements thereon;
 
- mortgages securing Debt owing by any Consolidated Subsidiary to Masco or
  another Consolidated Subsidiary;
 
- mortgages on property of a corporation existing at the time such corporation
  is merged or consolidated with us or a Consolidated Subsidiary or at the time
  of a sale, lease or other disposition of the properties of the corporation or
  firm as an entirety or substantially as an entirety to us or a Consolidated
  Subsidiary, provided that no such mortgage shall extend to any other Principal
  Property of Masco or any Consolidated Subsidiary or any shares of capital
  stock or any indebtedness of any Consolidated Subsidiary which owns or leases
  a Principal Property;
 
- mortgages on our property or a Consolidated Subsidiary's property in favor of
  the United States of America, any state thereof, or any other country, or any
  political subdivision of any thereof, to secure payments pursuant to any
  contract or statute, including Debt of the pollution control or industrial
  revenue bond type, or to secure any indebtedness incurred for the purpose of
  financing all or any part of
 
                                        9

 
  the purchase price or the cost of construction of the property subject to such
  mortgages; or
 
- one or more extensions, renewals or replacements, in whole or in part, of
  mortgages existing at the date of the Senior Debt Indenture or any mortgage
  referred to in the preceding five bullet points as long as those extensions,
  renewals or replacements do not increase the amount of Debt secured by the
  mortgage or cover any additional property.
 
     Notwithstanding the above, we may, and may permit any Consolidated
Subsidiary to, issue, assume or guarantee secured Debt which would otherwise be
subject to the foregoing restrictions, provided that after giving effect thereto
the total of the aggregate amount of such Debt then outstanding, excluding
secured Debt permitted under the foregoing exceptions, and the aggregate amount
of Attributable Debt in respect of sale and leaseback arrangements at such time,
does not exceed 5% of Consolidated Net Tangible Assets, determined as of a date
not more than 90 days prior thereto.
 
     The Subordinated Debt Indenture does not include negative pledge
provisions.
 
     Limitation on Sale and Leaseback Arrangements.  Under the Senior Debt
Indenture, we and our Consolidated Subsidiaries are not allowed to enter into
any sale and leaseback arrangement involving a Principal Property which has a
term of more than three years, except for sale and leaseback arrangements
between us and a Consolidated Subsidiary or between Consolidated Subsidiaries,
unless:
 
- we or the Consolidated Subsidiary could incur Debt secured by a mortgage on
  that Principal Property at least equal to the amount of Attributable Debt
  resulting from that sale and leaseback transaction without having to equally
  and ratably secure the senior debt securities in the manner described above
  under "Negative Pledge"; or
 
- we apply an amount equal to the greater of the net proceeds of the sale of the
  Principal Property or the fair market value of the Principal Property within
  120 days of the effective date of the sale and leaseback arrangement to the
  retirement of our or a Consolidated Subsidiary's Funded Debt, including the
  senior debt securities.
 
     However, we cannot satisfy the second test by retiring:
 
- Funded Debt that we were otherwise obligated to repay within the 120-day
  period;
 
- Funded Debt owned by us or by a Consolidated Subsidiary; or
 
- Funded Debt that is subordinated in right of payment to the senior debt
  securities.
 
     The Subordinated Debt Indenture does not include any limitations on sale
and leaseback arrangements.
 
     Consolidation, Merger or Sale of Assets. The Senior Debt Indenture provides
that we will not consolidate or merge with or into any other corporation and
will not sell or convey our property as an entirety, or substantially as an
entirety, to another corporation if, as a result of such action, any Principal
Property would become subject to a mortgage, unless either:
 
- such mortgage could be created pursuant to Section 10.04 of the Senior Debt
  Indenture without equally and ratably securing the senior debt securities; or
 
- the senior debt securities shall be secured prior to the Debt secured by such
  mortgage.
 
     Each of the indentures provides that we may consolidate or merge or sell
all or substantially all of our assets if:
 
- we are the continuing corporation or if we are not the continuing corporation,
  such continuing corporation is organized and existing under the laws of the
  United States of America or any state thereof or the District of Columbia and
  assumes by supplemental indenture the due and punctual payment of the
  principal of, and the premium, if any, and interest on the debt securities and
  the due and punctual performance and observance of all of the covenants and
  conditions of the
 
                                        10

 
  applicable indenture to be performed by us; and
 
- we are not, or such continuing corporation is not, in default in the
  performance of any such covenant or condition immediately after such merger,
  consolidation or sale of assets.
 
DEFINITIONS
 
     "Attributable Debt" in respect of a sale and leaseback arrangement is
defined in the Senior Debt Indenture to mean, at the time of determination, the
lesser of:
 
- the fair value of the property, as determined by our board of directors,
  subject to such arrangement; or
 
- the present value, discounted at the rate per annum equal to the interest
  borne by fixed rate senior debt securities or the yield to maturity at the
  time of issuance of any Original Issue Discount Securities determined on a
  weighted average basis, of the total obligations of the lessee for rental
  payments during the remaining term of the lease included in such arrangement,
  including any period for which such lease has been extended or may, at the
  option of the lessor, be extended, or until the earliest date on which the
  lessee may terminate such lease upon payment of a penalty, in which case the
  rental payment shall include such penalty, after excluding all amounts
  required to be paid on account of maintenance and repairs, insurance, taxes,
  assessments, water and utility rates and similar charges;
 
provided, however, that there shall not be deemed to be any Attributable Debt in
respect of a sale and leaseback arrangement if:
 
- such arrangement does not involve a Principal Property;
 
- we or a Consolidated Subsidiary would be entitled pursuant to the provisions
  of Section 10.04(a) of the Senior Debt Indenture to issue, assume or guarantee
  Debt secured by a mortgage upon the property involved in such arrangement
  without equally and ratably securing the senior debt securities; or
 
- the greater of the net proceeds of such arrangement or the fair market value
  of the property so leased has been applied to the retirement, other than any
  mandatory retirement or by way of payment at maturity, of our Funded Debt or
  any Consolidated Subsidiary's Funded Debt, other than Funded Debt owed by us
  or any Consolidated Subsidiary and other than Funded Debt which is
  subordinated in payment of principal or interest to the senior debt
  securities.
 
     "Consolidated Net Tangible Assets" is defined in the Senior Debt Indenture
as the aggregate amount of our assets less applicable reserves and the aggregate
amount of assets less applicable reserves of the Consolidated Subsidiaries after
deducting therefrom:
 
- all current liabilities, excluding any such liabilities deemed to be Funded
  Debt;
 
- all goodwill, trade names, trademarks, patents, unamortized debt discount and
  expense and other like intangibles; and
 
- all investments in any Subsidiary other than a Consolidated Subsidiary, in all
  cases computed in accordance with the generally accepted accounting principles
  and which under generally accepted accounting principles would appear on a
  consolidated balance sheet of Masco and its Consolidated Subsidiaries.
 
     "Consolidated Subsidiary" is defined in the Senior Debt Indenture to mean
each Subsidiary other than any Subsidiary the accounts of which:
 
- are not required by generally accepted accounting principles to be
  consolidated with our accounts for financial reporting purposes;
 
- were not consolidated with our accounts in our then most recent annual report
  to stockholders; and
 
- are not intended by us to be consolidated with our accounts in our next annual
  report to stockholders;
 
                                        11

 
provided, however, that the term "Consolidated Subsidiary" shall not include:
 
- any Subsidiary which is principally engaged in
 
  - owning, leasing, dealing in or developing real property, or
 
  - purchasing or financing accounts receivable, making loans, extending credit
    or other activities of a character conducted by a finance company, or
 
- any Subsidiary, substantially all of the business, properties or assets of
  which were acquired after the date of the Senior Debt Indenture whether by way
  of merger, consolidation, purchase or otherwise,
 
unless in each case our board of directors thereafter designates such Subsidiary
a Consolidated Subsidiary for the purposes of the Senior Debt Indenture.
 
     "Debt" is defined in the Senior Debt Indenture to mean any indebtedness for
money borrowed and any Funded Debt.
 
     "Funded Debt" is defined in the Senior Debt Indenture to mean indebtedness
maturing more than 12 months from the date of the determination thereof or
having a maturity of less than 12 months but renewable or extendible at the
option of the borrower beyond 12 months from the date of such determination:
 
- for money borrowed; or
 
- incurred in connection with the acquisition of property, to the extent that
  indebtedness in connection with acquisitions is represented by any notes,
  bonds, debentures or similar evidences of indebtedness, for which we or any
  Consolidated Subsidiary is directly or contingently liable or which is secured
  by our property or the property of a Consolidated Subsidiary.
 
     "Mortgage" is defined in the Senior Debt Indenture to mean a mortgage,
security interest, pledge, lien or other encumbrance.
 
     "Original Issue Discount Security" is defined in both indentures to mean
any debt security which provides for an amount less than the principal amount
thereof to be due and payable upon a declaration of acceleration of the maturity
thereof.
 
     "Principal Property" is defined in the Senior Debt Indenture to mean any
manufacturing plant or research or engineering facility located within the
United States of America or Puerto Rico owned or leased by us or any
Consolidated Subsidiary unless, in the opinion of our board of directors, such
plant or facility is not of material importance to the total business conducted
by us and our Consolidated Subsidiaries as an entirety.
 
     "Subsidiary" is defined in both indentures to mean any corporation of which
at least a majority of the outstanding stock having voting power under ordinary
circumstances to elect a majority of the board of directors of said corporation
shall at the time be owned by us, or by us and one or more Subsidiaries, or by
one or more Subsidiaries.
 
EVENTS OF DEFAULT, WAIVER AND NOTICE
 
     The indentures provide that the following events will be events of default
with respect to the debt securities of a series:
 
- we default in the payment of any interest on the debt securities of that
  series for more than 30 days;
 
- we default in the payment of any principal or premium on the debt securities
  of that series on the date that payment was due;
 
- we breach any of the other covenants applicable to that series of debt
  securities and that breach continues for more than 90 days after we receive
  notice from the trustee or the holders of at least 25% of the aggregate
  principal amount of debt securities of that series;
 
- we commence bankruptcy or insolvency proceedings or consent to any bankruptcy
  relief sought against us; or
 
                                        12

 
- we become involved in involuntary bankruptcy or insolvency proceedings and an
  order for relief is entered against us, if that order remains in effect for
  more than 60 consecutive days.
 
     The trustee or the holders of 25% of the aggregate principal amount of debt
securities of a series may declare all of the debt securities of that series to
be due and payable immediately if an event of default with respect to a payment
occurs. The trustee or the holders of 25% of the aggregate principal amount of
debt securities of each affected series voting as one class may declare all of
the debt securities of each affected series due and payable immediately if an
event of default with respect to a breach of a covenant occurs. The trustee or
the holders of 25% of the aggregate principal amount of debt securities
outstanding under the indenture voting as one class may declare all of the debt
securities outstanding under the indenture due and payable immediately if a
bankruptcy event of default occurs. The holders of a majority of the aggregate
principal amount of the debt securities of the applicable series or number of
series described in this paragraph may annul a declaration or waive a past
default except for a continuing payment default. If any of the affected debt
securities are Original Issue Discount Securities, by principal amount we mean
the amount that the holders would be entitled to receive by the terms of that
debt security if the debt security were declared immediately due and payable.
 
     The holders of a majority in principal amount of the debt securities of any
or all series affected and then outstanding shall have the right to direct the
time, method and place of conducting any proceeding for any remedy available to
the applicable trustee under the indentures. Notwithstanding the foregoing, a
trustee shall have the right to decline to follow any such direction if such
trustee is advised by counsel that the action so directed may not lawfully be
taken or if such trustee determines that such action would be unjustly
prejudicial to the holders not taking part in such direction or would involve
such trustee in personal liability.
 
     Each indenture requires that we file a certificate each year with the
applicable trustee stating that there are no defaults under the indenture. Each
indenture permits the applicable trustee to withhold notice to holders of debt
securities of any default other than a payment default if the trustee considers
it in the best interests of the holders.
 
MODIFICATION OF INDENTURES
 
     We can enter into a supplemental indenture with the applicable trustee to
modify any provision of the applicable indenture or any series of debt
securities without obtaining the consent of the holders of any debt securities
if the modification does not adversely affect the holders in any material
respect. In addition, we can generally enter into a supplemental indenture with
the applicable trustee to modify any provision of the indenture or any series of
debt securities if we obtain the consent of the holders of a majority of the
aggregate principal amount of debt securities of each affected series voting as
one class. However, we need the consent of each affected holder in order to:
 
- change the date on which any payment of principal or interest on the debt
  security is due;
 
- reduce the amount of any principal, interest or premium due on any debt
  security;
 
- change the currency or location of any payment;
 
- impair the right of any holder to bring suit for any payment after its due
  date; or
 
- reduce the percentage in principal amount of debt securities required to
  consent to any modification or waiver of any provision of the indenture or the
  debt securities.
 
CONCERNING THE TRUSTEES
 
     Each trustee is a depository for funds of, makes loans to and performs
other services for us from time to time in the normal course of business.
 
                                        13

 
FORM OF DEBT SECURITIES
 
     Each debt security will be represented either by a certificate issued in
definitive form to a particular investor or by one or more global securities
representing the entire issuance of securities issued at one time. Certificated
securities in definitive form and global securities will be issued in registered
form. Definitive securities name you or your nominee as the owner of the
security and, in order to transfer or exchange these securities or to receive
payments other than interest or other interim payments, you or your nominee must
physically deliver the securities to the trustee, registrar, paying agent or
other agent, as applicable. Global securities name a depositary or its nominee
as the owner of the debt securities represented by the global securities. The
depositary maintains a computerized system that will reflect each investor's
beneficial ownership of the securities through an account maintained by the
investor with its broker/dealer, bank, trust company or other representative, as
we explain more fully below under "Global Securities."
 
GLOBAL SECURITIES
 
     We may issue the debt securities of any series in the form of one or more
fully registered global securities that will be deposited with a depositary or
with a nominee for a depositary identified in the prospectus supplement relating
to such series and registered in the name of the depositary or its nominee. In
that case, one or more global securities will be issued in a denomination or
aggregate denominations equal to the portion of the aggregate principal or face
amount of outstanding registered securities of the series to be represented by
such global securities. Unless and until the depositary exchanges a global
security in whole for securities in definitive registered form, the global
security may not be transferred except as a whole by the depositary to a nominee
of the depositary or by a nominee of the depositary to the depositary or another
nominee of the depositary or by the depositary or any of its nominees to a
successor of the depositary or a nominee of such successor.
 
     If not described below, any specific terms of the depositary arrangement
with respect to any portion of a series of securities to be represented by a
global security will be described in the prospectus supplement relating to such
series. We anticipate that the following provisions will apply to all depositary
arrangements.
 
     Ownership of beneficial interests in a global security will be limited to
persons that have accounts with the depositary for such global security
("participants") or persons that may hold interests through participants. Upon
the issuance of a global security, the depositary for such global security will
credit, on its book-entry registration and transfer system, the participants'
accounts with the respective principal or face amounts of the securities
represented by such global security beneficially owned by such participants. The
accounts to be credited shall be designated by any dealers, underwriters or
agents participating in the distribution of such securities. Ownership of
beneficial interests in such global security will be shown on, and the transfer
of such ownership interests will be effected only through, records maintained by
the depositary for such global security, with respect to interests of
participants, and on the records of participants, with respect to interests of
persons holding through participants. The laws of some states may require that
some purchasers of securities take physical delivery of such securities in
definitive form. Such limits and such laws may impair the ability to own,
transfer or pledge beneficial interests in global securities. So long as the
depositary for a global security, or its nominee, is the registered owner of
such global security, such depositary or such nominee, as the case may be, will
be considered the sole owner or holder of the debt securities represented by
such global security for all purposes under the indentures. Except as set forth
below, owners of beneficial interests in a global security will not be entitled
to have the securities represented by such global security registered in their
names, will not receive or be entitled to receive physical delivery of such
securities in definitive form and will not be considered the owners or holders
thereof under the indentures. Accordingly, each
 
                                        14

 
person owning a beneficial interest in a global security must rely on the
procedures of the depositary for such global security and, if such person is not
a participant, on the procedures of the participant through which such person
owns its interest, to exercise any rights of a holder under either indenture. We
understand that under existing industry practices, if we request any action of
holders or if an owner of a beneficial interest in a global security desires to
give or take any action which a holder is entitled to give or take under either
indenture, the depositary for such global security would authorize the
participants holding the relevant beneficial interests to give or take such
action, and such participants would authorize beneficial owners owning through
such participants to give or take such action or would otherwise act upon the
instructions of beneficial owners holding through them.
 
     Principal, premium, if any, and interest payments on debt securities
represented by a global security registered in the name of a depositary or its
nominee will be made to such depositary or its nominee, as the case may be, as
the registered owner of such global security. We and the trustees or any of our
or their agents will not have any responsibility or liability for any aspect of
the records relating to or payments made on account of beneficial ownership
interests in such global security or for maintaining, supervising or reviewing
any records relating to such beneficial ownership interests.
 
     We expect that the depositary for any debt securities represented by a
global security, upon receipt of any payment of principal, premium, interest or
other distribution of underlying securities or commodities to holders in respect
of such global security, will immediately credit participants' accounts in
amounts proportionate to their respective beneficial interests in such global
security as shown on the records of such depositary. We also expect that
payments by participants to owners of beneficial interests in such global
security held through such participants will be governed by standing customer
instructions and customary practices, as is now the case with the securities
held for the accounts of customers in bearer form or registered in "street
name," and will be the responsibility of such participants.
 
     If the depositary for any debt securities represented by a global security
is at any time unwilling or unable to continue as depositary or ceases to be a
clearing agency registered under the Securities Exchange Act of 1934, and we do
not appoint a successor depositary registered as a clearing agency under the
Exchange Act within 90 days, we will issue such debt securities in definitive
form in exchange for such global security. In addition, we may at any time and
in our sole discretion determine not to have any of the debt securities of a
series represented by one or more global securities and, in such event, will
issue debt securities of such series in definitive form in exchange for all of
the global security or securities representing such debt securities. Any
securities issued in definitive form in exchange for a global security will be
registered in such name or names as the depositary shall instruct the relevant
trustee. We expect that such instructions will be based upon directions received
by the depositary from participants with respect to ownership of beneficial
interests in such global security.
 
                          DESCRIPTION OF CAPITAL STOCK
 
     The following description of the material terms of our capital stock is
based on the provisions of our amended and restated certificate of
incorporation. For more information as to how you can obtain a current copy of
our certificate of incorporation, see "Where You Can Find More Information."
 
     Our amended and restated certificate of incorporation authorizes the
issuance of one million shares of preferred stock, par value $1.00 per share and
1.4 billion shares of common stock, par value $1.00 per share.
 
                                        15

 
PREFERRED STOCK
 
     We may issue preferred stock from time to time in one or more series,
without stockholder approval. Subject to limitations prescribed by law, our
board of directors is authorized to determine the voting powers, if any,
designations and powers, preferences and rights, and the qualifications,
limitations or restrictions thereof, for each series of preferred stock that may
be issued and to fix the number of shares of each series of preferred stock.
 
     The prospectus supplement relating to any series of preferred stock will
describe the dividend rights of that series of preferred stock. Holders of
preferred stock of each series will be entitled to receive, when and as declared
by our board of directors out of funds legally available for the payment of
dividends, dividends, which may be cumulative or noncumulative, at the rate
determined by our board of directors for that series and set forth in the
prospectus supplement, as well as any further participation rights in dividend
distributions, if any. Dividends on the preferred stock will accrue from the
date fixed by our board of directors for that series. Unless we have declared
and paid in full all dividends payable on all of our outstanding preferred stock
for the current period, we will not be allowed to make any dividend payments on
our common stock.
 
     The terms, if any, on which preferred stock of any series may be redeemed
will be described in the related prospectus supplement. If we decide to redeem
fewer than all of the outstanding shares of preferred stock of any series, we
will determine the method of selecting which shares to redeem.
 
     The prospectus supplement relating to any series of preferred stock that is
convertible will state the terms on which shares of that series are convertible
into shares of another class of stock of Masco.
 
     In the event of our voluntary or involuntary liquidation, before any
distribution of assets will be made to the holders of our common stock, the
holders of the preferred stock of each series will be entitled to receive out of
our assets available for distribution to our shareholders the liquidation price
per share determined by our board of directors prior to the issuance of the
preferred stock of that series and described in the applicable prospectus
supplement as well as any declared and unpaid dividends on those shares. The
holders of all series of preferred stock are entitled to share ratably, in
accordance with the respective amounts payable on their shares, in any
distribution upon liquidation which is not sufficient to pay in full the
aggregate amounts payable on all of those shares.
 
     The preferred stock of a series issued pursuant to this Prospectus will not
be entitled to vote, except as provided in the applicable prospectus supplement,
unless required by applicable law. Unless otherwise indicated in the prospectus
supplement relating to a series of preferred stock, each share of a series will
be entitled to one vote on matters on which holders of that series are entitled
to vote.
 
     As of September 30, 2002, there were approximately 16,700 shares of series
B convertible preferred stock outstanding. These preferred shares are
convertible into approximately 16,700,000 shares of common stock, subject to
adjustment. Each share of series B preferred stock is entitled to receive the
same dividends as, and in general has voting rights equivalent to those of, the
shares of common stock into which such preferred stock is convertible. Shares of
series B preferred stock vote as a class as required by Delaware law and are
subject to certain restrictions on transfer.
 
COMMON STOCK
 
     Holders of common stock are entitled to one vote per share on matters to be
voted on by our stockholders and, subject to the rights of the holders of any
preferred stock of Masco then outstanding, to receive dividends, if any, when
declared by our board of directors in its discretion out of legally available
funds. Upon any liquidation or dissolution of Masco, holders of common stock are
entitled to receive pro rata all assets remaining after payment of all
liabilities and liquidation of any shares of any
 
                                        16

 
preferred stock at the time outstanding. Holders of common stock have no
preemptive or other subscription rights, and there are no conversion rights or
redemption or sinking fund provisions with respect to common stock. As of
September 30, 2002, there were approximately 493,240,000 shares of our common
stock outstanding and approximately 20,601,000 shares reserved for issuance upon
exercise of outstanding stock options. All of our outstanding common stock is
fully paid and non-assessable and all of the shares of common stock that may be
offered with this prospectus will be fully paid and non-assessable.
 
     The transfer agent and registrar for our common stock is The Bank of New
York, New York, New York.
 
STOCKHOLDER RIGHTS AGREEMENT
 
     We have a stockholder rights agreement which provides that each share of
our outstanding common stock has one-half of one right to purchase one
one-thousandth of a share of preferred stock. The purchase price per one
one-thousandth of a preferred share under the stockholder rights agreement is
$100. Our board of directors may, at its option, redeem all of the outstanding
rights at a redemption price of $0.01 per right, subject to adjustment, prior to
the time that an acquiring person obtains 15% or more of our outstanding common
stock. The rights will expire on December 6, 2005 unless earlier redeemed or
exchanged by us.
 
     The rights under our stockholder rights agreement are evidenced by the
outstanding certificates representing our common stock but will be represented
by separate certificates approximately 10 days after someone, other than we or
any of our subsidiaries or employee benefit plans, acquires at least 15% of our
outstanding common stock, or approximately 10 days after someone commences a
tender offer that would result in that person owning at least 15% of our
outstanding common stock.
 
     If an acquiring person obtains or has the right to obtain at least 15% of
our outstanding common stock, then each right will entitle the holder to
purchase for $100 either a number of shares of our common stock having a then
current market value of $200 or a number of shares of common stock of the
acquiring person having a then current market value of $200. After an acquiring
person obtains 15% or more, but less than 50%, of our outstanding common stock,
our board of directors may, at its option, exchange all or part of the then
outstanding and exercisable rights for shares of our common stock, at an
exchange ratio of two shares of common stock per right. Any rights obtained by a
person acquiring at least 15% of our outstanding common stock will be null and
void.
 
     Our stockholder rights agreement has anti-takeover effects. The rights may
cause substantial dilution to a person or group that attempts to acquire us
without conditioning the offer on a substantial number of rights being acquired,
redeemed or declared invalid. Accordingly, the existence of the rights may deter
acquirors from making takeover proposals or tender offers. However, the rights
are not intended to prevent a takeover, but rather are designed to enhance the
ability of our board of directors to negotiate with an acquiror on behalf of all
of the stockholders. In addition, the rights should not interfere with a proxy
contest.
 
                        DESCRIPTION OF DEPOSITARY SHARES
 
     We may, at our option, elect to offer fractional shares of preferred stock
rather than full shares of preferred stock. If we exercise this option, we will
issue to the public receipts for depositary shares, and each of these depositary
shares will represent a fraction (to be set forth in the applicable prospectus
supplement) of a share of a particular series of preferred stock.
 
     The shares of any series of preferred stock underlying the depositary
shares will be deposited under a deposit agreement between us and a bank or
trust company selected by us. The
 
                                        17

 
depositary will have its principal office in the United States and a combined
capital and surplus of at least $50,000,000. Subject to the terms of the deposit
agreement, each owner of a depositary share will be entitled, in proportion to
the applicable fraction of a share of preferred stock underlying the depositary
share, to all of the rights and preferences of the preferred stock underlying
that depositary share. Those rights may include dividend, voting, redemption,
conversion and liquidation rights.
 
     The depositary shares will be evidenced by depositary receipts issued under
a deposit agreement. Depositary receipts will be distributed to those persons
purchasing the fractional shares of preferred stock underlying the depositary
shares, in accordance with the terms of the offering. The following description
of the material terms of the deposit agreement, the depositary shares and the
depositary receipts is only a summary and you should refer to the forms of the
deposit agreement and depositary receipts that will be filed with the SEC in
connection with the offering of the specific depositary shares.
 
     Pending the preparation of definitive engraved depositary receipts, the
depositary may, upon our written order, issue temporary depositary receipts
substantially identical to the definitive depositary receipts but not in
definitive form. These temporary depositary receipts entitle their holders to
all of the rights of definitive depositary receipts. Temporary depositary
receipts will then be exchangeable for definitive depositary receipts at our
expense.
 
     Dividends and Other Distributions. The depositary will distribute all cash
dividends or other cash distributions received with respect to the underlying
stock to the record holders of depositary shares in proportion to the number of
depositary shares owned by those holders.
 
     If there is a distribution other than in cash, the depositary will
distribute property received by it to the record holders of depositary shares
that are entitled to receive the distribution, unless the depositary determines
that it is not feasible to make the distribution. If this occurs, the depositary
may, with our approval, sell the property and distribute the net proceeds from
the sale to the applicable holders.
 
     Withdrawal of Underlying Preferred Stock. Unless we say otherwise in a
prospectus supplement, holders may surrender depositary receipts at the
principal office of the depositary and, upon payment of any unpaid amount due to
the depositary, be entitled to receive the number of whole shares of underlying
preferred stock and all money and other property represented by the related
depositary shares. We will not issue any partial shares of preferred stock. If
the holder delivers depositary receipts evidencing a number of depositary shares
that represent more than a whole number of shares of preferred stock, the
depositary will issue a new depositary receipt evidencing the excess number of
depositary shares to that holder.
 
     Redemption of Depositary Shares. If a series of preferred stock represented
by depositary shares is subject to redemption, the depositary shares will be
redeemed from the proceeds received by the depositary resulting from the
redemption, in whole or in part, of that series of underlying stock held by the
depositary. The redemption price per depositary share will be equal to the
applicable fraction of the redemption price per share payable with respect to
that series of underlying stock. Whenever we redeem shares of underlying stock
that are held by the depositary, the depositary will redeem, as of the same
redemption date, the number of depositary shares representing the shares of
underlying stock so redeemed. If fewer than all of the depositary shares are to
be redeemed, the depositary shares to be redeemed will be selected by lot or
proportionately, as may be determined by the depositary.
 
     Voting. Upon receipt of notice of any meeting at which the holders of the
underlying stock are entitled to vote, the depositary will mail the information
contained in the notice to the record holders of the depositary shares
underlying the preferred stock. Each record holder of the depositary shares on
the record date (which will be the same date as the record date for the
underlying stock) will be entitled to instruct the depositary as to the exercise
of the
 
                                        18

 
voting rights pertaining to the amount of the underlying stock represented by
that holder's depositary shares. The depositary will then try, as far as
practicable, to vote the number of shares of preferred stock underlying those
depositary shares in accordance with those instructions, and we will agree to
take all actions which may be deemed necessary by the depositary to enable the
depositary to do so. The depositary will not vote the underlying shares to the
extent it does not receive specific instructions with respect to the depositary
shares representing the preferred stock.
 
     Conversion of Preferred Stock. If the prospectus supplement relating to the
depositary shares says that the deposited preferred stock is convertible into
common stock or shares of another series of preferred stock of Masco, the
following will apply. The depositary shares, as such, will not be convertible
into any securities of Masco. Rather, any holder of the depositary shares may
surrender the related depositary receipts to the depositary with written
instructions to instruct us to cause conversion of the preferred stock
represented by the depositary shares into or for whole shares of common stock or
shares of another series of preferred stock of Masco, as applicable. Upon
receipt of those instructions and any amounts payable by the holder in
connection with the conversion, we will cause the conversion using the same
procedures as those provided for conversion of the deposited preferred stock. If
only some of the depositary shares are to be converted, a new depositary receipt
or receipts will be issued for any depositary shares not to be converted.
 
     Amendment and Termination of the Deposit Agreement. The form of depositary
receipt evidencing the depositary shares and any provision of the deposit
agreement may at any time be amended by agreement between us and the depositary.
However, any amendment which materially and adversely alters the rights of the
holders of depositary shares will not be effective unless the amendment has been
approved by the holders of at least a majority of the depositary shares then
outstanding. The deposit agreement may be terminated by us or by the depositary
only if (a) all outstanding depositary shares have been redeemed or converted
for any other securities into which the underlying preferred stock is
convertible or (b) there has been a final distribution of the underlying stock
in connection with our liquidation, dissolution or winding up and the underlying
stock has been distributed to the holders of depositary receipts.
 
     Charges of Depositary. We will pay all transfer and other taxes and
governmental charges arising solely from the existence of the depositary
arrangements. We will also pay charges of the depositary in connection with the
initial deposit of the underlying stock and any redemption of the underlying
stock. Holders of depositary receipts will pay other transfer and other taxes
and governmental charges and those other charges, including a fee for any
permitted withdrawal of shares of underlying stock upon surrender of depositary
receipts, as are expressly provided in the deposit agreement to be for their
accounts.
 
     Reports. The depositary will forward to holders of depositary receipts all
reports and communications from us that we deliver to the depositary and that we
are required to furnish to the holders of the underlying stock.
 
     Limitation on Liability. Neither we nor the depositary will be liable if
either of us is prevented or delayed by law or any circumstance beyond our
control in performing our respective obligations under the deposit agreement.
Our obligations and those of the depositary will be limited to performance in
good faith of our respective duties under the deposit agreement. Neither we nor
the depositary will be obligated to prosecute or defend any legal proceeding in
respect of any depositary shares or underlying stock unless satisfactory
indemnity is furnished. We and the depositary may rely upon written advice of
counsel or accountants, or upon information provided by persons presenting
underlying stock for deposit, holders of depositary receipts or other persons
believed to be competent and on documents believed to be genuine.
 
     Resignation and Removal of Depositary. The depositary may resign at any
time by delivering notice to us of its election to resign.
 
                                        19

 
We may remove the depositary at any time. Any resignation or removal will take
effect upon the appointment of a successor depositary and its acceptance of the
appointment. The successor depositary must be appointed within 60 days after
delivery of the notice of resignation or removal and must be a bank or trust
company having its principal office in the United States and having a combined
capital and surplus of at least $50,000,000.
 
        DESCRIPTION OF SHARE PURCHASE CONTRACTS AND SHARE PURCHASE UNITS
 
     We may issue share purchase contracts representing contracts obligating
holders to purchase from us, and us to sell to the holders, shares of our common
stock at a future date or dates. The price per share of common stock and the
number of shares of common stock may be fixed at the time the share purchase
contracts are issued or may be determined by reference to a specific formula set
forth in the share purchase contracts and described in the applicable prospectus
supplement.
 
     The share purchase contracts may be issued separately or as a part of share
purchase units consisting of a share purchase contract and:
 
- our debt securities,
 
- our preferred stock, or
 
- debt obligations of third parties, including U.S. Government securities;
 
in each case, securing the holders' obligations to purchase the common stock
under the share purchase contracts.
 
     The share purchase contracts may require us to make periodic payments to
the holders of the share purchase units or vice versa, and those payments may be
unsecured or prefunded on some basis. The share purchase contracts may require
holders to secure their obligations in a specified manner and, in certain
circumstances, we may deliver newly issued prepaid share purchase contracts,
often known as prepaid securities, upon release to a holder of any collateral
securing such holder's obligations under the original share purchase contract.
 
     The applicable prospectus supplement will describe the material terms of
any share purchase contracts or share purchase units and, if applicable, prepaid
securities. The description in the applicable prospectus supplement will not
contain all of the information that you may find useful. For more information,
you should review the share purchase contracts, the collateral arrangements and
depositary arrangements, if applicable, relating to such share purchase
contracts or share purchase units and, if applicable the prepaid securities and
the document pursuant to which the prepaid securities will be issued. These
documents will be filed with the SEC promptly after the offering of the share
purchase contracts or share purchase units. Material United States federal
income tax considerations applicable to the share purchase contracts and the
share purchase units will also be discussed in the applicable prospectus
supplement.
 
                              PLAN OF DISTRIBUTION
 
     We may sell the securities being offered by this prospectus in four ways:
 
- directly to purchasers;
 
- through agents;
 
- through underwriters; and
 
- through dealers.
 
     We may directly solicit offers to purchase securities, or we may designate
agents to solicit such offers. We will, in the prospectus supplement relating to
such offering, name any agent that could be viewed as an underwriter under the
Securities Act of 1933 and describe any commissions we must pay. Any such agent
will be acting on a best efforts basis for the period
 
                                        20

 
of its appointment or, if indicated in the applicable prospectus supplement, on
a firm commitment basis. Agents, dealers and underwriters may be customers of,
engage in transactions with, or perform services for us in the ordinary course
of business.
 
     As one of the means of direct issuance of securities, we may utilize the
services of any available electronic auction system to conduct an electronic
"dutch auction" of the offered securities among potential purchasers who are
eligible to participate in the auction of those offered securities, if so
described in the prospectus supplement.
 
     If any underwriters are utilized in the sale of the securities in respect
of which this prospectus is delivered, we will enter into an underwriting
agreement with them at the time of sale to them and we will set forth in the
prospectus supplement relating to such offering their names and the terms of our
agreement with them.
 
     If a dealer is utilized in the sale of the securities in respect of which
the prospectus is delivered, we will sell such securities to the dealer, as
principal. The dealer may then resell such securities to the public at varying
prices to be determined by such dealer at the time of resale.
 
     Remarketing firms, agents, underwriters and dealers may be entitled under
agreements which they may enter into with us to indemnification by us against
some types of civil liabilities, including liabilities under the Securities Act
of 1933, and may be customers of, engage in transactions with or perform
services for us in the ordinary course of business.
 
     If we so indicate in the prospectus supplement, we will authorize agents,
underwriters or dealers to solicit offers by the types of purchasers specified
in the prospectus supplement to purchase offered securities from us at the
public offering price set forth in the prospectus supplement pursuant to delayed
delivery contracts providing for payment and delivery on a specified date in the
future. Such contracts will be subject to only those conditions set forth in the
prospectus supplement, and the prospectus supplement will set forth the
commission payable for solicitation of such offers.
 
                                 LEGAL OPINIONS
 
     The legality of the securities in respect of which this prospectus is being
delivered will be passed on for us by John R. Leekley, Senior Vice President and
General Counsel of Masco, and for the underwriters, if any, by Davis Polk &
Wardwell, 450 Lexington Avenue, New York, New York 10017. Mr. Leekley is a Masco
stockholder and a holder of options to purchase shares of our common stock.
Davis Polk & Wardwell performs legal services from time to time for us and some
of our related companies.
 
                                    EXPERTS
 
     The financial statements incorporated in this prospectus by reference to
the Annual Report on Form 10-K for the year ended December 31, 2001, have been
so incorporated in reliance on the report of PricewaterhouseCoopers LLP,
independent accountants, given on the authority of said firm as experts in
auditing and accounting.
 
                      WHERE YOU CAN FIND MORE INFORMATION
 
     We have filed this prospectus as part of a registration statement on Form
S-3 with the SEC. The registration statement contains exhibits and other
information that are not
 
                                        21

 
contained in this prospectus. In particular, the registration statement includes
as exhibits copies of the forms of our senior debt and subordinated debt
indentures. Our descriptions in this prospectus of the provisions of documents
filed as exhibits to the registration statement or otherwise filed with the SEC
are only summaries of the documents' material terms. If you want a complete
description of the content of the documents, you should obtain the documents by
following the procedures described in the paragraph below.
 
     We file annual, quarterly and special reports and other information with
the SEC. You may read and copy any document we file at the SEC's Public
Reference Room located at 450 Fifth Street, N.W., Washington, D.C. 20549. Please
call the SEC at 1-800-SEC-0330 for further information on the Public Reference
Rooms. You may also read our SEC filings, including the complete registration
statement and all of the exhibits to it, through the SEC's web site at
www.sec.gov.
 
     The SEC allows us to "incorporate by reference" much of the information we
file with them, which means that we can disclose important information to you by
referring you directly to those publicly available documents. The information
incorporated by reference is considered to be part of this prospectus. In
addition, information we file with the SEC in the future will automatically
update and supersede information contained in this prospectus and the
accompanying prospectus supplement.
 
     We incorporate by reference the documents listed below and any future
filings made with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the
Securities Exchange Act of 1934 until we sell all of the securities we are
offering with this prospectus:
 
- Our Annual Report on Form 10-K for the year ended December 31, 2001;
 
- Our Current Reports on Form 8-K dated May 14, 2002, June 19, 2002, June 27,
  2002, July 30, 2002, August 20, 2002, September 18, 2002, September 19, 2002,
  October 4, 2002, October 16, 2002 and October 29, 2002;
 
- Our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2002, June
  30, 2002 and September 30, 2002; and
 
- The description of our common stock contained in the amendment on Form 8 dated
  May 22, 1991 to our registration statement on Form 8-A and the description of
  our preferred stock purchase rights contained in the amendment on Form
  8-A12B/A dated March 18, 1999 to our registration statement on Form 8-A.
 
     You may obtain free copies of any of these documents by writing or
telephoning us at 21001 Van Born Road, Taylor, Michigan, 48180, Attention:
Samuel Cypert, Vice President, Investor Relations, (313) 274-7400, or by
visiting our web site at www.masco.com. However, the information on our website
is not a part of this prospectus.
 
                                        22

 
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                                  $500,000,000
 
                               MASCO CORPORATION
 
                              4.80% NOTES DUE 2015
 
                      ------------------------------------
                             PROSPECTUS SUPPLEMENT
                      ------------------------------------
 
MERRILL LYNCH & CO.
                                   CITIGROUP
                                                             JPMORGAN
 
                                  JUNE 7, 2005
 
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