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

VOTE BY INTERNET - www.proxyvote.com

Use the Internet to transmit your voting instructions and for electronic delivery, of information, up until 11:59 P.M. Eastern Time, June 15, 2016. Have your proxy card in hand when you access the web site and follow the instructions to obtain your records and to create an electronic voting instruction form.

VOTE BY PHONE - 1-800-690-6903

Use any touch-tone telephone to transmit your voting instructions and for electronic delivery, of information, up until 11:59 P.M. Eastern Time, June 15, 2016. Have your proxy card in hand when you call and then follow the instructions.

VOTE BY MAIL

Mark, sign and date your proxy card and return it in the postage-paid envelope we have provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717.

1.

Election of Directors (for a term expiring in 2019)

The Board of Directors recommends you vote FOR proposals 2, 3, 4 and 5.

For

Against

Abstain

Yes

No

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 and 10-K/Annual Report Combo are available at www.proxyvote.com

NATURAL GAS SERVICES GROUP, INC.

THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS

ANNUAL MEETING OF SHAREHOLDERS JUNE 16, 2016.

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 16, 2016, 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, 3, 4 AND 5. 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 above named company.

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 02, 2016 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 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.

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