Pentasil-containing catalysts for increasing the octane number of straight-run naphtha cuts without using hydrogen-containing gas should have a number of functions [1-3], and stability of operation for a long time is the most important one. The goal of these studies was to select modifiers for pentasil-containing catalysts which could increase the duration of their regeneration-free work in increasing the octane number of gas condensate naphtha cuts. High-silica powdered zeolites of the ZVM and ZVN pentasil family with SiO2 :Al2O3 equal to 44 and 54 (mole), respectively, were used as the initial zeolites.