Nicor Inc.
                                                                       Form 10-Q
                                                                    Exhibit 31.1

                                  CERTIFICATION

I, Thomas L. Fisher, Chairman and Chief Executive Officer of
Nicor Inc., certify that:

1) I have reviewed this quarterly report on Form 10-Q of Nicor Inc.;

2) Based on my knowledge, this report does not contain any untrue statement of a
   material fact or omit to state a material fact necessary to make the
   statements made, in light of the circumstances under which such statements
   were made, not misleading with respect to the period covered by this report;

3) Based on my knowledge, the financial statements, and other financial
   information included in this report, fairly present in all material respects
   the financial condition, results of operations and cash flows of the
   registrant as of, and for, the periods presented in this report;

4) The registrant's other certifying officer(s) and I are responsible for
   establishing and maintaining disclosure controls and procedures (as defined
   in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant and have:

 a) Designed such disclosure controls and procedures, or caused such disclosure
    controls and procedures to be designed under our supervision, to ensure that
    material information relating to the registrant, including its consolidated
    subsidiaries, is made known to us by others within those entities,
    particularly during the period in which this report is being prepared;

 b) Evaluated the effectiveness of the registrant's disclosure controls and
    procedures and presented in this report our conclusions about the
    effectiveness of the disclosure controls and procedures, as of the end of
    the period covered by this report based on such evaluation; and

 c) Disclosed in this report any change in the registrant's internal control
    over financial reporting that occurred during the registrant's most recent
    fiscal quarter (the registrant's fourth fiscal quarter in the case of an
    annual report) that has materially affected, or is reasonably likely to
    materially affect, the registrant's internal control over financial
    reporting; and

5) The registrant's other certifying officer(s) and I have disclosed, based on
   our most recent evaluation of internal control over financial reporting, to
   the registrant's auditors and the audit committee of the registrant's board
   of directors (or persons performing the equivalent functions):

 a) All significant deficiencies and material weaknesses in the design or
    operation of internal control over financial reporting which are reasonably
    likely to adversely affect the registrant's ability to record, process,
    summarize and report financial information; and

 b) Any fraud, whether or not material, that involves management or other
    employees who have a significant role in the registrant's internal control
    over financial reporting.



   Date August 4, 2003           /s/ THOMAS L. FISHER
        --------------          -----------------------------------
                                Thomas L. Fisher
                                Chairman and Chief Executive Officer
<PAGE>

                                                                      Nicor Inc.
                                                                       Form 10-Q
                                                                    Exhibit 31.2

                                  CERTIFICATION

I, Kathleen L. Halloran, Executive Vice President Finance and
Administration of Nicor Inc., certify that:

1) I have reviewed this quarterly report on Form 10-Q of Nicor Inc.;

2) Based on my knowledge, this report does not contain any untrue statement of a
   material fact or omit to state a material fact necessary to make the
   statements made, in light of the circumstances under which such statements
   were made, not misleading with respect to the period covered by this report;

3) Based on my knowledge, the financial statements, and other financial
   information included in this report, fairly present in all material respects
   the financial condition, results of operations and cash flows of the
   registrant as of, and for, the periods presented in this report;

4) The registrant's other certifying officer(s) and I are responsible for
   establishing and maintaining disclosure controls and procedures (as defined
   in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant and have:

 a) Designed such disclosure controls and procedures, or caused such disclosure
    controls and procedures to be designed under our supervision, to ensure that
    material information relating to the registrant, including its consolidated
    subsidiaries, is made known to us by others within those entities,
    particularly during the period in which this report is being prepared;

 b) Evaluated the effectiveness of the registrant's disclosure controls and
    procedures and presented in this report our conclusions about the
    effectiveness of the disclosure controls and procedures, as of the end of
    the period covered by this report based on such evaluation; and

 c) Disclosed in this report any change in the registrant's internal control
    over financial reporting that occurred during the registrant's most recent
    fiscal quarter (the registrant's fourth fiscal quarter in the case of an
    annual report) that has materially affected, or is reasonably likely to
    materially affect, the registrant's internal control over financial
    reporting; and

5) The registrant's other certifying officer(s) and I have disclosed, based on
   our most recent evaluation of internal control over financial reporting, to
   the registrant's auditors and the audit committee of the registrant's board
   of directors (or persons performing the equivalent functions):

 a) All significant deficiencies and material weaknesses in the design or
    operation of internal control over financial reporting which are reasonably
    likely to adversely affect the registrant's ability to record, process,
    summarize and report financial information; and

 b) Any fraud, whether or not material, that involves management or other
    employees who have a significant role in the registrant's internal control
    over financial reporting.


   Date August 4, 2003          /s/ KATHLEEN L. HALLORAN
        --------------          -------------------------
                                Kathleen L. Halloran
                                Executive Vice President
                                Finance and Administration