Thermal decomposition of potassium chlorate in the presence of various additives is studied using thermogravimetric analysis and differential thermal analysis. Catalytic effects of metal oxides with comparable surface areas are compared, and the catalytic effects of a number of nonoxide additives are also studied. The nonoxide additives show catalytic activities similar to the corresponding metal oxides. Metal cations and their electron configurations determine the catalytic activity of various compounds. Metal cations with partially filledd shells have the highest activity, transition metal cations with completely emptyd orbitals are moderated active, and metal cations with completely filledd shells or noble gas configurations have minimum activity.