Northern Technologies International (NTIC) 10-K 2013 FY Annual report

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in the Registration Statement on Form S-3 (File No. 333-185271) and Registration Statements on Form S-8 (File Nos. 333-140244, 333-140245 and 333-171828) of Northern Technologies International Corporation and Subsidiaries of our report dated November 22, 2013, which appears on page 55 of this annual report on Form 10-K for the fiscal year ended August 31, 2013.

/s/ Baker Tilly Virchow Krause, LLP

Minneapolis, Minnesota

November 22, 2013