Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in Registration Statement No. 333-209534 on Form S-8 of our report dated June 19, 2019, appearing in this Annual Report on Form 11-K of the Olin Corporation Contributing Employee Ownership Plan for the year ended December 31, 2018.

/s/ Brown Smith Wallace, LLC

St. Louis, Missouri

June 19, 2019

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