It was shown that phenylethyl (ethylbenzene) hydroperoxide (EBHP) decomposes in an acetonitrile solution in an argon atmosphere in the presence of a styrene epoxide (SE)-p-toluenesulfonic acid (TSA) binary system yielding acetophenone and methylphenylcarbinol in a molar ratio of 1: 1. The expression for the EBHP degradation rate v = k (p)[TSA](1)[SE](0)[EBHP](0) is equivalent to the relationships obtained earlier for the rates of oxygen uptake by the binary system and the buildup of the oxidation product. The temperature dependence of the specific rate of degradation is given by k (p) = 1 x 10(14)exp (-111.8 kJ mol(-1)/RT) s(-1) (333-348 K).