Coked catalysts may often be regenerated by in situ oxidation. Being a highly exothermic process, the high regeneration temperature that may result is of ultimate concern. The possibility of a thermal runaway, however, has traditionally been ignored. In this study, the theory of parametric sensitivity was extended to investigate the regeneration of a single coked catalyst pellet. Our results showed that the sensitivity of the pellet temperature Varies with different operating conditions. The sensitivities become critical when the burning rate and the migration rate of oxygen inside the pellet become equivalently important. It is found that the system sensitivities with different operating parameters behave similarly if these sensitive parameters affect the system through a similar path. For example, the gas concentration and the film transfer-ability affect the regeneration behavior through the pellet boundary. The initial temperature and coke contents, on the other hand, change the reaction condition uniformly throughout the entire catalyst. As a result, maximum sensitivities were observed to occur at different operating conditions.