The paper presents the results of kinetic investigations of the dehydrogenation of para-ethyltoluene on a grade K-24 oxide iron-chromium-potassium catalyst. Kinetic models of target and secondary conversions of para-ethyltoluene have been obtained. The mechanism of catalytic conversions of this compound is put forward. The obtained kinetic description of the dehydrogenation of para-ethyltoluene can be used for the modelling and calculation of an industrial reactor for para-methylstyrene synthesis.