The effect of axial distribution of a fixed amount of catalyst on the performance of an isothermal reactor, in which both heterogeneous and homogeneous reactions occur, is investigated. Analytical solutions for first-order reactions reveal that a uniform axial distribution of catalyst is optimal except for the case of negligible mass transfer resistance when all catalyst distributions give the same result. In cases where the catalyst enhances the rate of homogeneous reaction, the competition between the heterogeneous reaction and the enhanced homogeneous reaction leads to an optimal step-width, whose size and location depend on the values of the physicochemical parameters.