The effect of gallium and its combination with zirconium on the acid and catalytic properties of pentasil in the upgrading of straight-run fractions in the absence of hydrogen was studied. Hydrogenation-dehydrogenation sites and medium-strength acid sites are formed upon the concurrent modification of phosphorus-containing N-Ultrasil by gallium and zirconium. An optimal ratio of these sites is achieved for Zr:Ga mass ratio 1:1 and this increases the rate of isomerization of nparaffins and the rate of aromatization of aliphatic and naphthenic hydrocarbons. Insertion of phosphorus into zeolite leads to an increased yield of liquid products due to weakening and redistribution of the acid sites.