CECO Environmental (CECO) 10-Q 2015 Q2 Quarterly report

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of CECO Environmental Corp. (the “Company”) on Form 10-Q for the three-month period ended June 30, 2015 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Jeffrey Lang, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, to the best of his knowledge and belief, that:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and

(2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company as of the dates and for the periods expressed in the Report.

/s/ Jeffrey Lang

Jeffrey Lang

Chief Executive Officer

Date: August 7, 2015