EXHIBIT 31.1
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CERTIFICATIONS

I, Charles W. Fischer, certify that:

1.   I have reviewed this quarterly report on Form 10-Q of Nexen 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 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 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 function):

     (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:    July 14, 2006                    /s/ Charles W. Fischer
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                                          Charles W. Fischer
                                          President and Chief Executive Officer