Exhibit 32.1

Certification

Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

(Subsections (a) and (b) of Section 1350, Chapter 63 of Title 18, United States Code)

Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (subsections (a) and (b) of Section 1350, Chapter 63 of Title 18, United States Code), the undersigned officer of RPM International Inc., a Delaware corporation (the “Company”), does hereby certify, to such officer’s knowledge, that:

(1) The Annual Report on Form 10-K for the period ended May 31, 2021 (the “Form 10-K”) of the Company 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 Form 10-K fairly presents, in all material respects, the financial condition and results of operations of the Company as of, and for, the periods presented in the Form 10-K.

Date: July 26, 2021

/s/ Frank C. Sullivan

Frank C. Sullivan

Chairman, President and Chief Executive Officer

The foregoing Certification is being furnished solely pursuant to 18 U.S.C. Section 1350 and is not being filed as part of the Form 10-K or as a separate disclosure document.

A signed original of this written statement required by Section 906 has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.