<PAGE>
Exhibit 24
POWER OF ATTORNEY
The undersigned, a director or officer of OM Group Inc., a Delaware
corporation (the "Company"), which anticipates filing with the Securities and
Exchange Commission (the "Commission") under the provisions of the Securities
Act of 1933 (the "Act") a Registration Statement on Form S-8 (together with any
and all subsequent amendments, including post-effective amendments, the
"Registration Statement") for purposes of registering 2,000,000 shares of Common
Stock with $.01 par value of the Company, to be offered pursuant to the OM
Group, Inc. 1998 Long-Term Incentive Compensation Plan, does hereby constitute
and appoint Michael J. Scott with full power of substitution and resubstitution,
as attorney to execute and file on behalf of the undersigned, in his capacity as
a director or officer of the Company, the Registration Statement and any and all
applications or other documents to be filed with the Commission pertaining to
the Registration Statement or registration contemplated thereby, with full power
and authority to do and perform any and all acts and things whatsoever required
or necessary to be done in the premises, as fully as to all intents and purposes
as he could do if personally present, hereby ratifying and approving the acts of
said attorney and any such substitution.
IN WITNESS WHEREOF, I have hereunto set my hand this 3rd day of October,
2000.
/s/ James P. Mooney
------------------------------
James P. Mooney
<PAGE>
Exhibit 24
POWER OF ATTORNEY
The undersigned, a director or officer of OM Group Inc., a Delaware
corporation (the "Company"), which anticipates filing with the Securities and
Exchange Commission (the "Commission") under the provisions of the Securities
Act of 1933 (the "Act") a Registration Statement on Form S-8 (together with any
and all subsequent amendments, including post-effective amendments, the
"Registration Statement") for purposes of registering 2,000,000 shares of Common
Stock with $.01 par value of the Company, to be offered pursuant to the OM
Group, Inc. 1998 Long-Term Incentive Compensation Plan, does hereby constitute
and appoint Michael J. Scott with full power of substitution and resubstitution,
as attorney to execute and file on behalf of the undersigned, in his capacity as
a director or officer of the Company, the Registration Statement and any and all
applications or other documents to be filed with the Commission pertaining to
the Registration Statement or registration contemplated thereby, with full power
and authority to do and perform any and all acts and things whatsoever required
or necessary to be done in the premises, as fully as to all intents and purposes
as he could do if personally present, hereby ratifying and approving the acts of
said attorney and any such substitution.
IN WITNESS WHEREOF, I have hereunto set my hand this 3rd day of October,
2000.
/s/ James M. Materna
------------------------------
James M. Materna
<PAGE>
Exhibit 24
POWER OF ATTORNEY
The undersigned, a director or officer of OM Group Inc., a Delaware
corporation (the "Company"), which anticipates filing with the Securities and
Exchange Commission (the "Commission") under the provisions of the Securities
Act of 1933 (the "Act") a Registration Statement on Form S-8 (together with any
and all subsequent amendments, including post-effective amendments, the
"Registration Statement") for purposes of registering 2,000,000 shares of Common
Stock with $.01 par value of the Company, to be offered pursuant to the OM
Group, Inc. 1998 Long-Term Incentive Compensation Plan, does hereby constitute
and appoint Michael J. Scott with full power of substitution and resubstitution,
as attorney to execute and file on behalf of the undersigned, in his capacity as
a director or officer of the Company, the Registration Statement and any and all
applications or other documents to be filed with the Commission pertaining to
the Registration Statement or registration contemplated thereby, with full power
and authority to do and perform any and all acts and things whatsoever required
or necessary to be done in the premises, as fully as to all intents and purposes
as he could do if personally present, hereby ratifying and approving the acts of
said attorney and any such substitution.
IN WITNESS WHEREOF, I have hereunto set my hand this 3rd day of October,
2000.
/s/ Lee R. Brodeur
------------------------------
Lee R. Brodeur
<PAGE>
Exhibit 24
POWER OF ATTORNEY
The undersigned, a director or officer of OM Group Inc., a Delaware
corporation (the "Company"), which anticipates filing with the Securities and
Exchange Commission (the "Commission") under the provisions of the Securities
Act of 1933 (the "Act") a Registration Statement on Form S-8 (together with any
and all subsequent amendments, including post-effective amendments, the
"Registration Statement") for purposes of registering 2,000,000 shares of Common
Stock with $.01 par value of the Company, to be offered pursuant to the OM
Group, Inc. 1998 Long-Term Incentive Compensation Plan, does hereby constitute
and appoint Michael J. Scott with full power of substitution and resubstitution,
as attorney to execute and file on behalf of the undersigned, in his capacity as
a director or officer of the Company, the Registration Statement and any and all
applications or other documents to be filed with the Commission pertaining to
the Registration Statement or registration contemplated thereby, with full power
and authority to do and perform any and all acts and things whatsoever required
or necessary to be done in the premises, as fully as to all intents and purposes
as he could do if personally present, hereby ratifying and approving the acts of
said attorney and any such substitution.
IN WITNESS WHEREOF, I have hereunto set my hand this 3rd day of October,
2000.
/s/ Frank E. Butler
------------------------------
Frank E. Butler
<PAGE>
Exhibit 24
POWER OF ATTORNEY
The undersigned, a director or officer of OM Group Inc., a Delaware
corporation (the "Company"), which anticipates filing with the Securities and
Exchange Commission (the "Commission") under the provisions of the Securities
Act of 1933 (the "Act") a Registration Statement on Form S-8 (together with any
and all subsequent amendments, including post-effective amendments, the
"Registration Statement") for purposes of registering 2,000,000 shares of Common
Stock with $.01 par value of the Company, to be offered pursuant to the OM
Group, Inc. 1998 Long-Term Incentive Compensation Plan, does hereby constitute
and appoint Michael J. Scott with full power of substitution and resubstitution,
as attorney to execute and file on behalf of the undersigned, in his capacity as
a director or officer of the Company, the Registration Statement and any and all
applications or other documents to be filed with the Commission pertaining to
the Registration Statement or registration contemplated thereby, with full power
and authority to do and perform any and all acts and things whatsoever required
or necessary to be done in the premises, as fully as to all intents and purposes
as he could do if personally present, hereby ratifying and approving the acts of
said attorney and any such substitution.
IN WITNESS WHEREOF, I have hereunto set my hand this 3rd day of October,
2000.
/s/ John E. Mooney
------------------------------
John E. Mooney
