September 19, 2018
United States Securities and Exchange Commission
Division of Corporation Finance
100 F Street, N.E.
Washington, D.C. 20549
Attention: Thomas Jones
| Re: | Request for Acceleration |
ClearSign Combustion Corporation - Registration Statement on Form S-3
(SEC File No. 333-227169)
Mr. Jones:
Pursuant to Rule 461 of the Securities Act of 1933, as amended, ClearSign Combustion Corporation (the “Company”) respectfully requests that its Registration Statement on Form S-3 (SEC File No. 333-227169) be ordered effective at 5:00 p.m., Washington, D.C. time, on September 21, 2018, or as soon thereafter as practicable. The Company requests that it be notified of such effectiveness by a telephone call to Melanie Figueroa at (917) 546-7707, or in her absence, Mary Ann Sapone at (310) 312-3258.
| Sincerely, | |||
| CLEARSIGN COMBUSTION CORPORATION | |||
| By: | /s/ Stephen E. Pirnat | ||
| Stephen E. Pirnat, Chief Executive Officer | |||