The capacity of pentasils to aromatize C-2-C-12 hydrocarbons is determined by a number of factors, in particular. the SiO2:Al2O3 ratio in the zeolite, the degree of decationization. the presence of a modifying additive and its-state in the reaction conditions, the amount of zeolite in the catalyst. and the conditions of preliminary activation. The effect of these parameters on conversion of these hydrocarbons in the presence of pentasil zeolites is intensively investigated in [1-3].