1 Exhibit 15.2 Acknowledgment of Independent Accountants Stockholders and Board of Directors OM Group, Inc. We are aware of the incorporation by reference in the following Registration Statements of OM Group, Inc. of our report dated May 10, 2000, relating to the unaudited condensed consolidated interim financial statements of OM Group, Inc. which are included in its Form 10-Q for the quarter ended March 31, 2000. Registration Number Description Filing Date - ------ ----------- ----------- 33-74674 OM Group, Inc. Long-Term Incentive Compensation Plan - Form S-8 Registration Statement - 1,015,625 Shares January 27, 1994 333-7529 OMG Americas, Inc. Employees' Profit Sharing Plan -- Form S-8 Registration Statement -- 250,000 Shares July 3, 1996 333-7531 OM Group, Inc. Non-Employee Directors' Equity Plan -- Form S-8 Registration Statement -- 250,000 Shares July 3, 1996 Pursuant to Rule 436(c) of the Securities Act of 1933 our report is not a part of the registration statements prepared or certified by accountants within the meaning of Section 7 or 11 of the Securities Act of 1933. /s/ Ernst & Young LLP --------------------- Ernst & Young LLP Cleveland, Ohio May 10, 2000 12