CexZr1-xO2 oxides prepared by a soft reactive grinding (SRG) procedure have been investigated as the catalysts for HCl oxidation. The results show that the catalytic activities and stabilities of CexZr1-xO2 oxides are remarkably dependent on the Ce/Zr ratio. A correlation between the physicochemical properties and catalytic performances of these samples reveals that the cubic phase in CexZr1-xO2 with higher oxygen storage capacity (OSC) is more active for HCl oxidation, but the tetragonal phase is crucial to the stability of the catalysts. The Ce0.5Zr0.5O2 catalyst with mixed phases and the highest OSC (80 mu mol(O2)gcat1) exhibits an excellent activity (1.89 g(Cl2) g(cat-)(1) h1 at 430 degrees C) and stability (300 h) in the target reaction. Kinetic studies show that both O-2 and HCl competed for the active sites rendering desorption of surface Cl as the rate-determining step. Accelerating the replacement of surface Cl by O-2 is essential for improving the activity of Ce-0.5Zr0.5O2.