Title of each class of securities to which the transaction applies:

Aggregate number of securities to which transaction applies:

Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11:

Proposed maximum aggregate value of transaction:

Total fee paid:

Amount Previously Paid:

Form, Schedule or Registration Statement No.:

Filing Party:

Date Filed:

NATURAL GAS SERVICES GROUP, INC.

508 WEST WALL STREET, SUITE 550

MIDLAND, TX 79701

ELECTRONIC DELIVERY OF FUTURE PROXY MATERIALS

If you would like to reduce the costs incurred by our company in mailing proxy materials, you can consent to receiving all future proxy statements, proxy cards and annual reports electronically via e-mail or the Internet. To sign up for electronic delivery, please follow the instructions above to vote using the Internet and, when prompted, indicate that you agree to receive or access proxy materials electronically in future years.

VOTE BY PHONE - 1-800-690-6903

VOTE BY MAIL

Withhold  

All   

For All

Except

To withhold authority to vote for any individual nominee(s), mark “For All Except” and write the number(s) of the nominee(s) on the line below.

The Board of Directors recommends you vote FOR the following:

1.

Election of Directors

¨

¨

¨

Nominees

01

David L. Bradshaw                        02    Willam F. Hughes, Jr.

Please indicate if you plan to attend this meeting

¨

¨

Please sign exactly as your name(s) appear(s) hereon. When signing as attorney, executor, administrator, or other fiduciary, please give full title as such. Joint owners should each sign personally. All holders must sign. If a corporation or partnership, please sign in full corporate or partnership name, by authorized officer.

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting: The Notice & Proxy Statement, 10-K/Annual Report Combo is/are available at www.proxyvote.com.

NATURAL GAS SERVICES GROUP, INC.

The shareholder(s) hereby appoint(s) Stephen C. Taylor and G. Larry Lawrence, or either of them, as proxies, each with the power to appoint his substitute, and hereby authorizes them to represent and to vote, as designated on the reverse side of this ballot, all of the shares of Common Stock of NATURAL GAS SERVICES GROUP, INC. that the shareholder(s) is/are entitled to vote at the Annual Meeting of Shareholders to be held at 8:30 AM, CDT on June 18, 2015, at the Petroleum Club of Midland, at 501 West Wall Street, Midland TX 79701, and any adjournment or postponement thereof.

THIS PROXY, WHEN PROPERLY EXECUTED WILL BE VOTED AS DIRECTED BY THE SHAREHOLDER(S). IF NO SUCH DIRECTIONS ARE MADE, THIS PROXY WILL BE VOTED FOR THE ELECTION OF THE NOMINEE LISTED ON THE REVERSE SIDE FOR THE BOARD OF DIRECTORS and FOR ITEMS 2 AND 3. IF ANY OTHER MATTER PROPERLY COMES BEFORE THE MEETING, THE PERSONS NAMED IN THE PROXY WILL VOTE IN THEIR DISCRETION.

PLEASE MARK, SIGN, DATE AND RETURN THIS PROXY CARD PROMPTLY USING THE ENCLOSED REPLY ENVELOPE.

Continued and to be signed on reverse side

NATURAL GAS SERVICES GROUP, INC.

Meeting Type: Annual Meeting

                   501 West Wall Street

                   Midland, TX 79701

You are receiving this communication because you hold shares in the company named above.

This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side).

We encourage you to access and review all of the important information contained in the proxy materials before voting.

See the reverse side of this notice to obtain proxy materials and voting instructions.

Proxy Materials Available to VIEW or RECEIVE:

How to View Online:

How to Request and Receive a PAPER or E-MAIL Copy:

1)  BY INTERNET:

www.proxyvote.com

2)  BY TELEPHONE:

1-800-579-1639

3)  BY E-MAIL*:

sendmaterial@proxyvote.com

*  If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow (located on the following page) in the subject line.

Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before June 4, 2015 to facilitate timely delivery.

— How To Vote —

Please Choose One of the Following Voting Methods

Vote In Person: If you choose to vote these shares in person at the meeting, you must request a “legal proxy.” To do so, please follow the instructions at www.proxyvote.com or request a paper copy of the materials, which will contain the appropriate instructions. Many shareholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance.

Vote By Internet: To vote now by Internet, go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow (located on the following page) available and follow the instructions.

Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a voting instruction form.

Voting Items

1.      

2.

3.

NOTE: