Optimal catalyst composition profiles have been computed for a bifunctional catalytic reaction occurring under isothermal conditions in a tubular reactor. Use of the maximum principle enables the optimal profile to be attained in a comparatively small number of iterations. Depending on the values of the kinetic parameters it is found that either a changing catalyst composition profile or a two-stage reactor containing the pure catalyst components gives an optimal yield. For some cases however, it appears that a constant catalyst composition profile gives yields close to the optimum.