Metal-support interaction in the catalytic combustion of toluene was studied using metal oxides with different acid-base properties as supports for Pd. The catalytic performance was correlated with XPS data and the reaction order for oxygen. These studies revealed that the affinity for oxygen of Pd surface changed according to the acid-base character of metal oxide over MgO, Al2O3, SiO2, SnO2, Nb2O5, and WO3. However, ZrO2 exhibited exceptional character in that metal Pd was unusually stabilized, which was derived from the weak interaction between Pd and support surface. The reason for high toluene combustion activity of Pd/ZrO2 was ascribed to the stabilization of metal Pd on ZrO2. (C) 2003 Elsevier Science B.V. All rights reserved.