Methods for the oxidation of aralkyl compounds have been examined with special reference to the oxidation of toluene and O-toluenesulphonamide. Catalytic aerial oxidations have been investigated as possible procedures with an industrial application. The stability of O-toluenesulphonamide towards oxidation is accounted for and the mechanism of oxidation of toluene by both homolytic and heterolytic bond fission is discussed. The preparation of saccharin by oxidation of O-toluenesulphonamide with manganese dioxide in acid solution is reported.