The effect of the chemical composition of zeolite catalysts in the CaLaHX form on their catalytic properties in isobutane alkylation with butylenes have been studied. Optimum concentrations of metal oxides providing a butylene conversion of 97-100 wt %, an alkylate yield that is close to the theoretical value (95-100 wt %), and a trimethylpentane (TMP) selectivity at a level of 73 wt % have been determined (wt %: Na2O, 0.5; CaO, 0.6; La2O3, 18.3). It has been found that there is a fair good correlation between the optimum chemical composition of the catalyst samples and their acidity determined by temperature-programmed desorption of ammonia.