**Exhibit 31.1**

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

I, G. Patrick Lynch, certify that:

| 1.     | I have reviewed this quarterly report on Form 10-QSB of Northern TechnologiesInternational Corporation;                                                                                                                                                                                                                                      |
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| 2.     | Based on my knowledge, this report does not contain any untrue statement of amaterial fact or omit to state a material fact necessary to make the statementsmade, in light of the circumstances under which such statements were made, notmisleading with respect to the period covered by this report;                                      |
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| 3.     | Based on my knowledge, the financial statements, and other financial informationincluded in this report, fairly present in all material respects the financialcondition, results of operations and cash flows of the small business issuer asof, and for, the periods presented in this report;                                              |
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| 4.     | The small business issuer’s other certifying officers and I are responsiblefor establishing and maintaining disclosure controls and procedures (as definedin Exchange Act Rules 13a-15(e) and 15d-15(e)) for the small business issuer andhave:                                                                                         |
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|   |                                                                                                                                                                                                                                                                                                                                         | (a)     Designed such disclosure controls andprocedures, or caused such disclosure controls and procedures to be designedunder our supervision, to ensure that material information relating to the smallbusiness issuer, including its consolidated subsidiaries, is made known to us byothers within those entities, particularly during the period in which thisreport is being prepared; |
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|   |                                                                                                                                                                                                                                                                                                                                         | (b)     Evaluated the effectiveness of the smallbusiness issuer’s disclosure controls and procedures and presented in thisreport our conclusions about the effectiveness of the disclosure controls andprocedures, as of the end of the period covered by this report based on suchevaluation; and |
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|   |                                                                                                                                                                                                                                                                                                                                         | (c)     Disclosed in this report any change in thesmall business issuer’s internal control over financial reporting thatoccurred during the small business issuer’s fourth quarter that hasmaterially affected, or is reasonably likely to materially affect, the smallbusiness 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 financialreporting, to the small business issuer’s auditors and the audit committeeof the small business issuer’s board of directors (or persons performingthe equivalent function): |
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|   |                                                                                                                                                                                                                                                                                                                                         | (a)     All significant deficiencies and materialweaknesses in the design or operation of internal controls over financialreporting which are reasonably likely to adversely affect the small businessissuer’s ability to record, process, summarize and report financialinformation; and |
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|   |                                                                                                                                                                                                                                                                                                                                         | (b)     Any fraud, whether or not material, thatinvolves management or other employees who have a significant role in the smallbusiness issuer’s internal controls over financial reporting. |

| Date:  July 12, 2007 |   |                                         |
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|                      |   | G.   Patrick Lynch                      |
|                      |   | President   and Chief Executive Officer |