Exhibit 99.1 CERTIFICATION Pursuant to Section 1350 of Chapter 63 of Title 18 of the United States Code I certify that, to the best of my knowledge, the Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2002 (the "10-Q") of GEO Specialty Chemicals, Inc. ("GEO") fully complies with the requirements of Section 15(d) of the Securities Exchange Act of 1934, and that the information contained in the 10-Q fairly presents, in all material respects, the financial condition and results of operations of GEO as of the dates and for the periods covered by the 10-Q. /s/ George P. Ahearn -------------------- George P. Ahearn President and Chief Executive Officer August 5, 2002