An analysis of the rate of formation of the desired product and of the selectivity has been carried out for composite catalysts wherein small particles of zeolite are distributed nonuniformly within a large particle of the more porous silica-alumina. Two nonuniform distributions have been analyzed, namely, (i) the composite-center distribution, where a uniform dilute region of zeolite in silica-alumina is surrounded by a silica-alumina matrix, and (ii) the composite-surface distribution, where a uniform dilute region is located around the pure silica-alumina matrix. Two reaction schemes, A→B→C and A→C→D, which fairly approximate the catalytic cracking process over the Zeolite/silica-alumina catalyst have been examined. The reaction scheme A→B→C is employed for the composite-center distribution, while the reaction scheme A→C→D is considered for the composite-surface distribution, because the overall rate of formation of the desired product can be thus optimized. There are conditions under which the selectivity can also be optimized