Kinetics of hydrogen peroxide decomposition over Pd/SiO2 catalyst was investigated as part of a larger project to determine the overall kinetics of hydrogen peroxide formation by Pd/SiO2 catalyzed direct combination of hydrogen and oxygen. A Pd oxidative/reductive cycle mechanism for the decomposition of H2O2 over Pd/SiO2 was proposed. A Rideal-Eley rate expression based on this mechanism was shown to accurately correlate experimental data over a wide range of H2O2 concentration and temperature. This rate equation was shown to also apply in the presence of stabilizing concentrations of H2SO4.