A study has been made of the oxidation of thiophenol by hydrogen peroxide under interphase catalysis conditions with the use of the following catalytic systems: 10-24% hydrogen peroxide, transition metal compounds (sodium tungstate, sodium and ammonium molybdates), and interphase transfer catalysts -quaternary ammonium salts (triethylbenzylammoniumbromide etc.). The rate and selectivity of oxidation are affected by the type of catalyst, the H2O2 concentration, the thiol/H2O2 ratio, the nature of the solvent, and the temperature and duration of the experiment. A 10% selectivity of thiol conversion into disulphides was achieved by the use of catalytic systems: Na2WO4 (30 min) and (NH4)(2)MoO4 (60 min), cetyltrimethylammoniumbromide, PhH/H2O2 ratio 1:3, CHCl3, 20 degrees C.