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 II-VI Incorporated (the "Corporation") on Form 10-Q for the period ending December 31, 2002 as filed with the Securities and Exchange Commission on the date hereof (the "Report"), each of the undersigned officers of the Corporation certifies, pursuant to 18 U.S.C. S.S. 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to his knowledge: (1) The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and (2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Corporation. Date: May 14, 2003 /s/ Carl J. Johnson Carl J. Johnson Chairman and Chief Executive Officer A signed original of this written statement required by Section 906 has been provided to II-VI Incorporated and will be retained by II-VI Incorporated and furnished to the Securities and Exchange Commission or its staff upon request. The foregoing certification is being furnished in accordance with Securities and Exchange Commission Release No. 34-47551 and shall not be considered filed as part of the Form 10-Q. * This certification is made solely for purposes of 18 U.S.C. Section 1350, subject to the knowledge standard contained therein, and not for any other purpose.