Natural Gas Services (NGS) 8-K Changes in Registrant's Certifying Accountant

Exhibit 16.1

June 10, 2020

Securities and Exchange Commission

100 F Street N.E.

Washington, D.C. 20549

We have been furnished with a copy of the response to Item 4.01 of Form 8-K for the event that occurred on June 4, 2020, to be filed by our former client, Natural Gas Services Group, Inc. We agree with the statements made in response to that Item insofar as they relate to our Firm.

Very truly yours,

/s/ BDO USA, LLP