Theoretical and experimental work on tubular reactors has shown that a high temperature reaction zone can be induced to move counter to the flow of reactants by conduction and/or radiation through the solid phase. This naturally occurring phenomenon represents a transient mode of operation that can be argued to be preferable to conventional modes of operation. In order to test this hypothesis the complete time and space dependent optimal temperature policy was generated for a tubular reactor subject to several catalyst decay laws. The solutions revealed that a critical parameter is the ratio of the activation energy for the main reaction to that for the catalyst decay reaction. For values of this ratio less than one, the optimum temperature profiles represent a low temperature reaction zone that occupies the entire active bed at all times, essentially a conventional mode of operation. However, for this ratio greater than one the profiles represent a short high temperature reaction zone that propagates with time along the length of the reactor. For a catalyst decay law independent of conversion, propagation in either axial direction was optimal, but for a decay law dependent upon conversion the optimization procedure only generated reverse propagating zones.