The oxidative decarboxylation of aryl, alpha,alpha-diaryl, or arylalkylacetic acids has been achieved by a 2-nitrobenzenesulfonyl peroxy radical intermediate (I) generated by the reaction of 2-nitrobenzenesulfonyl chloride with potassium superoxide at -20 degrees C in dry acetonitrile. (C) 1998 Elsevier Science Ltd. All rights reserved.