An investigation has been made of the kinetic relationships governing the decomposition of ethylbenzene hydroperoxide (EBHP) in the presence of a complex molybdenum catalyst (KMK). Data obtained by processing the curves of product accumulation and EBHP consumption by the initial rates method are given. With account taken of published data and the composition of the products, it is concluded that, at the initial moment, there are two routes by which EBHP decomposition occurs. The presence of molybdenum in low states of oxidation in the KMK has been demonstrated by spectral methods.