Nicor
          Inc.
 Form
          10-K
 Exhibit
          31.1
 
 **CERTIFICATION**
 
 I,
          Russ
          M. Strobel, certify that:
 
 1)  I
          have
          reviewed this annual report on Form 10-K 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)) and internal control over financial reporting
          (as
          defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) 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)  Designed
          such internal control over financial reporting, or caused such internal
          control
          over financial reporting to be designed under our supervision, to provide
          reasonable assurance regarding the reliability of financial reporting and
          the
          preparation of financial statements for external purposes in accordance
          with
          generally accepted accounting principles;
 
 c)  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
 
 d)  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 signficant role in the registrant's internal control over financial
            reporting.
 
 Date
                February
                    24, 2006
                
                /s/
                    RUSS M. STROBELRuss
                    M. StrobelChairman,
                    President and Chief Executive
                    Officer