<PAGE>

                                  EXHIBIT 31.1

                               CCFNB BANCORP, INC.

                          CEO CERTIFICATION PURSUANT TO
                               SECTION 302 OF THE
                           SARBANES-OXLEY ACT OF 2002

I, Lance O. Diehl, certify that:

      1.    I have reviewed this quarterly report on Form 10-Q of CCFNB Bancorp,
            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 officers 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 officers 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: May 10, 2005
                                         /s/ Lance O. Diehl
                                         ---------------------------
                                            Lance O. Diehl
                                            Chief Executive Officer

                                      26