United States

Securities and Exchange Commission

Washington, D.C. 20549

FORM 10-Q/A

Amendment No. 1

(Mark One)

For the quarterly period ended June 30, 2011

or

For the transition period from             to             

Commission File Number: 000-50216

ADA-ES, INC.

(Exact name of registrant as specified in its charter)

(303) 734-1727

(Registrant’s telephone number, including area code)

Not Applicable

(Former name, former address and former fiscal year, if changed since last report)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  x    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  x    No  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See definition of “large accelerated filer,” “accelerated filer,” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act. (Check one):    Yes  ¨    No  x

APPLICABLE ONLY TO ISSUERS INVOLVED IN BANKRUPTCY

PROCEEDINGS DURING THE PRECEDING FIVE YEARS:

Indicate by check mark whether the registrant has filed all documents and reports required to be filed by Sections 12, 13 or 15(d) of the Securities Exchange Act of 1934 subsequent to the distribution of securities under a plan confirmed by a court.    Yes  ¨    No  ¨

APPLICABLE ONLY TO CORPORATE ISSUERS:

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date.

EXPLANATORY NOTE

This Amendment No. 1 (“Amendment No. 1”) to the Form 10-Q of ADA-ES, Inc. (the “Company”) for the quarterly period ended June 30, 2011 (originally filed on August 12, 2011) (the “Quarterly Report”), is filed for the purpose of filing new copies of Exhibit 10.33, Exhibit 10.84 and Exhibit 10.85 (the “Amended Exhibits”) and for adding a notation in the exhibit index that the non-public information has been separately filed with the Securities and Exchange Commission (“SEC”). The Company sought confidential treatment for portions of the Amended Exhibits and, following correspondence with the SEC, has restored certain portions of the Amended Exhibits that were previously redacted.

Except for the foregoing, this Amendment No. 1 does not amend the Quarterly Report in any way and does not modify or update any disclosures contained in the Quarterly Report, which continues to speak as of the original date of the Quarterly Report. Accordingly, this Amendment No. 1 should be read in conjunction with the Quarterly Report and the Company’s other filings made with the SEC subsequent to the Quarterly Report.

In accordance with Rule 12b-15 under the Securities Exchange Act of 1934, as amended, this Amendment No. 1 includes updated certifications from the Registrant’s Chief Executive Officer and Chief Financial Officer.

With the exception of the Amended Exhibits and the notation stating that the non-public information has been separately filed with the SEC, the Exhibits are unchanged and copies of the Exhibits are incorporated by reference as indicated.

SIGNATURES

In accordance with the requirements of the Securities Exchange Act of 1934, the Registrant caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

EXHIBIT INDEX