The effect of high-temperature steam treatment of high-silica zeolites (HSZ) modified with zinc and gallium on their activity and catalyticproperties with respect to the aromatization of lower C3-C4 alkanes is studied. The introduction of modifying gallium and zinc additives into H-HSZ improves the activity and selectivity of the zeolite-containing catalysts with respect to the formation of aromatic hydrocarbons. The high-temperature steam treatment is shown to result in partial dealumination of the zeolite and decrease in the proton-donor power and concentration of acidic centers. The reactions applying to catalysts treated in this way yield products with a lower content of aromatic (especially polycyclic) hydrocarbons and a higher concentration of lower olefins.