Abstract The photosensitized electron-transfer oxidation of a series of ethyl sulfides RSEt (1, R= C 12 H 25; 2, PhCH 2 CH 2; 3, PhCH 2; 4, PhCMe 2; 5, Ph 2 CH) has been examined in acetonitrile and the product distribution discussed on the basis of the mechanisms proposed. In nitrogen-flushed solutions, cleaved alcohols and alkenes are formed, whereas under oxygen, in reactions that are 10–70 times faster, sulfoxides and cleaved aldehydes ...