EXHIBIT 31.2
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CERTIFICATIONS

I, Marvin F. Romanow, 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 Rule
     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:    May 1, 2006                              /s/ Marvin F. Romanow
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                                                  Marvin F. Romanow
                                                  Executive Vice President
                                                  and Chief Financial Officer