Exhibit 32.1

CERTIFICATION PURSUANT TO 18 U.S.C. §1350, AS ADOPTED PURSUANT TO SECTION 906 OF
THE SARBANES-OXLEY ACT OF 2002

In accordance with 18 U.S.C. §1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, Michael R. Boyce, Chief Executive Officer of PQ Corporation (the “Registrant”) and James P. Cox, Vice President and Chief Financial Officer of the Registrant, each hereby certifies that, to the best of his knowledge:

1. the Registrant’s Quarterly Report on Form 10-Q for the period ended March 31, 2006, to which this Certification is attached as Exhibit 32.1 (the “Periodic Report”), fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended;

2. The information contained in the Periodic Report fairly presents, in all material respects, the financial condition of the Registrant at the end of the period covered by the Periodic Report and results of operations of the Registrant for the periods covered by the Periodic Report.

Date: June 23, 2006

	By:	/s/ MICHAEL R. BOYCE
		Michael R. Boyce
		Chief Executive Officer



	By:	/s/ JAMES P. COX
		James P. Cox
		Vice President and Chief Financial Officer

PQ CORP 10-Q