HZSM-5, HFerrosilicate and HBorosilicate were prepared and then modified by impregnation each of several metallic components. These catalysts were examined for their crystal structure, surface characteristics, and acidic properties and also applied for two reactions, alkylation and disproportionation of toluene. The objective here is to make a study of the selectivity enhancement for p-xylene from both reactions. These solid acid catalysts turned out to have one strong and one weak acid sites, which appear to be relate to the Bronsted and Lewis acids, respectively. In particular, the strong acid was lowered in its amount and weakened in its strength by metal impregnation as well as by the increase of metal loading. For both reactions the p-xylene selectivity was observed higher over HFerrosilicate than over the other two catalysts. For the three catalysts of H-form, the p-xylene selectivity was markedly enhanced by metal impregnation, the degree being most distinguished over HZSM-5 catalyst. Such enhancement in the p-xylene selectivity may be at-tributed to weakening of the strong acid and pore-blocking caused by metal impregnation.