**Exhibit 31.1**

**CERTIFICATION PURSUANT TO SECTION 302(a) OF THE  SARBANES-OXLEY ACT OF 2002**

I, Philip M. Lynch, certify that:

| 1.                                                                                                                                                                                                                                                                                                                                                                                                   | I have reviewed this quarterly report on Form 10-QSB of Northern   Technologies International Corporation;                                                                                                                                                                                                                                                                                                                                       |
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| 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;                                       |
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| 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 small business issuer as of, and   for, the periods presented in this report;                                               |
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| 4.       The small business   issuer’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)) for the small business issuer and have:                                                                                            |
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|                                                                                                                                                                                                                                                                                                                                                                                                 | (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 small business issuer, 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; |
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|                                                                                                                                                                                                                                                                                                                                                                                                 | (b)       Evaluated the effectiveness   of the small business issuer’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                                                                                         |
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|                                                                                                                                                                                                                                                                                                                                                                                                 | (c)       Disclosed   in this report any change in the small   business issuer’s internal control over financial reporting that   occurred during the small business issuer’s   current reported quarter that has materially affected, or is reasonably likely   to materially affect, the small business   issuer’s internal control over financial reporting; and                            |
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| 5.       The small business   issuer’s other certifying officers and I have disclosed, based on our most   recent evaluation of internal controls over financial reporting, to the small   business issuer’s auditors and the audit committee of the small business   issuer’s board of directors (or persons performing the equivalent function): |
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|                                                                                                                                                                                                                                                                                                                                                                                                 | (a)       All significant   deficiencies and material weaknesses in the design or operation of internal   controls over financial reporting which are reasonably likely to adversely   affect the small business issuer’s ability to record, process, summarize and   report financial information; and                                                                                                  |
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|                                                                                                                                                                                                                                                                                                                                                                                                 | (b)       Any fraud, whether or not   material, that involves management or other employees who have a significant   role in the small business issuer’s internal controls over financial   reporting.                                                                                                                                                                                                   |

 

| Date:  July 15, 2005 |                                                                    |
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|                      | Philip M. Lynch                                                    |
|                      | Chairman of the Board of Directors &   Chief Executive Officer |