Abstract Techniques for the optimization of axially dispersed packed bed reactors having catalyst decay are developed. A weak maximum principle is presented along with an efficient computational algorithm for synthesizing the optimal policies. Singular perturbation methods are used to solve the very stiff state and adjoint equations resulting at high Peclet numbers. Numerical examples are worked to illustrate the salient features of the optimization technique as well as to give insight into the nature of the optimal policies. A certain amount of axial dispersion is found to actually improve the performance of the reactors in some cases due to the “washing out” of the hot spots which cause accelerated catalyst deactivation.