The acyloxy group of 2-acyloxy-2H-azirines has been displaced by carboxylic acids to generate the corresponding 2-acyloxy-2H-azirines by using potassium iodide as a promotor. This metal-free method can be performed with a wide scope of substrates readily generating products in moderate to high yields. It also represents an example of nucleophilic substitution between esters and carboxylic acids under metal-free reaction conditions for the first time.