POWER OF ATTORNEY     The undersigned director of OM Group, Inc. (the “Company”), a Delaware corporation, whichanticipates filing with the Securities and Exchange Commission, Washington, D.C., under theprovisions of the Securities Exchange Act of 1934, as amended, an Annual Report on Form 10-K forthe Company’s fiscal year ended December 31, 2009, hereby constitutes and appoints JOSEPH M.SCAMINACE and KENNETH HABER, with full power of substitution and resubstitution, as attorney tosign for the undersigned and in his or her name, place and stead, as director of said Company, saidAnnual Report and any and all amendments and exhibits thereto, and any and all applications anddocuments to be filed with the Securities and Exchange Commission pertaining to such Annual Report,with full power and authority to do and perform any and all acts and things whatsoever requisite,necessary or advisable to be done in the premises, as fully and for all intents and purposes as theundersigned could do if personally present, hereby approving the acts of said attorney and any suchsubstitute.     IN WITNESS WHEREOF, this Power of Attorney has been signed this 20th day of January, 2010.           /s/David L. Pugh    David L. Pugh      
 

 
     POWER OF ATTORNEY     The undersigned director of OM Group, Inc. (the “Company”), a Delaware corporation, whichanticipates filing with the Securities and Exchange Commission, Washington, D.C., under theprovisions of the Securities Exchange Act of 1934, as amended, an Annual Report on Form 10-K forthe Company’s fiscal year ended December 31, 2009, hereby constitutes and appoints JOSEPH M.SCAMINACE and KENNETH HABER, with full power of substitution and resubstitution, as attorney tosign for the undersigned and in his or her name, place and stead, as director of said Company, saidAnnual Report and any and all amendments and exhibits thereto, and any and all applications anddocuments to be filed with the Securities and Exchange Commission pertaining to such Annual Report,with full power and authority to do and perform any and all acts and things whatsoever requisite,necessary or advisable to be done in the premises, as fully and for all intents and purposes as theundersigned could do if personally present, hereby approving the acts of said attorney and any suchsubstitute.     IN WITNESS WHEREOF, this Power of Attorney has been signed this 19th day of January, 2010.           /s/Gordon A. Ulsh    Gordon A. Ulsh      
 

 
     POWER OF ATTORNEY     The undersigned director of OM Group, Inc. (the “Company”), a Delaware corporation, whichanticipates filing with the Securities and Exchange Commission, Washington, D.C., under theprovisions of the Securities Exchange Act of 1934, as amended, an Annual Report on Form 10-K forthe Company’s fiscal year ended December 31, 2009, hereby constitutes and appoints JOSEPH M.SCAMINACE and KENNETH HABER, with full power of substitution and resubstitution, as attorney tosign for the undersigned and in his or her name, place and stead, as director of said Company, saidAnnual Report and any and all amendments and exhibits thereto, and any and all applications anddocuments to be filed with the Securities and Exchange Commission pertaining to such Annual Report,with full power and authority to do and perform any and all acts and things whatsoever requisite,necessary or advisable to be done in the premises, as fully and for all intents and purposes as theundersigned could do if personally present, hereby approving the acts of said attorney and any suchsubstitute.     IN WITNESS WHEREOF, this Power of Attorney has been signed this 20th day of January, 2010.           /s/Steven J. Demetriou     Steven J. Demetriou      
 

 
     POWER OF ATTORNEY     The undersigned director of OM Group, Inc. (the “Company”), a Delaware corporation, whichanticipates filing with the Securities and Exchange Commission, Washington, D.C., under theprovisions of the Securities Exchange Act of 1934, as amended, an Annual Report on Form 10-K forthe Company’s fiscal year ended December 31, 2009, hereby constitutes and appoints JOSEPH M.SCAMINACE and KENNETH HABER, with full power of substitution and resubstitution, as attorney tosign for the undersigned and in his or her name, place and stead, as director of said Company, saidAnnual Report and any and all amendments and exhibits thereto, and any and all applications anddocuments to be filed with the Securities and Exchange Commission pertaining to such Annual Report,with full power and authority to do and perform any and all acts and things whatsoever requisite,necessary or advisable to be done in the premises, as fully and for all intents and purposes as theundersigned could do if personally present, hereby approving the acts of said attorney and any suchsubstitute.     IN WITNESS WHEREOF, this Power of Attorney has been signed this 19th day of January, 2010.           /s/Katharine L. Plourde     Katharine L. Plourde      
 

 
     POWER OF ATTORNEY     The undersigned director of OM Group, Inc. (the “Company”), a Delaware corporation, whichanticipates filing with the Securities and Exchange Commission, Washington, D.C., under theprovisions of the Securities Exchange Act of 1934, as amended, an Annual Report on Form 10-K forthe Company’s fiscal year ended December 31, 2009, hereby constitutes and appoints JOSEPH M.SCAMINACE and KENNETH HABER, with full power of substitution and resubstitution, as attorney tosign for the undersigned and in his or her name, place and stead, as director of said Company, saidAnnual Report and any and all amendments and exhibits thereto, and any and all applications anddocuments to be filed with the Securities and Exchange Commission pertaining to such Annual Report,with full power and authority to do and perform any and all acts and things whatsoever requisite,necessary or advisable to be done in the premises, as fully and for all intents and purposes as theundersigned could do if personally present, hereby approving the acts of said attorney and any suchsubstitute.     IN WITNESS WHEREOF, this Power of Attorney has been signed this 18th day of January, 2010.           /s/William J. Reidy     William J. Reidy