The inhibiting action of potassium iodide and bromide on the oxidation of the binary system of styrene epoxide + p-toluenesulfonic acid and on the hydroperoxide decomposition in the presence of the binary system was revealed. The inhibition mechanism is complex. During the course of the inhibition, the active form of the inhibitor is regenerated, which interacts, according to the kinetic data, with the transient species formed in the binary mixture.