Cerium-zirconium mixed oxides (CexZr(1-x)O2), precalcined at 900 degrees C in dry air, were supplied by Rhodia Terres Rares as monophasic solid solutions. Introduction of some zirconium atoms in the ceria lattice by isomorphous substitution clearly influences the final properties of these materials as long as the cubic structure of ceria is maintained, Modifications in oxygen storage capacity (OSC measurements), redox properties (CO TPR), and oxygen exchange processes (TPIE) were studied. Ce0.63Zr0.37O2 was shown to have the most promising properties with-the largest OSC at 400 degrees C and the highest reactivity in O-2 exchange. All mixed oxides are able to exchange very large amounts of oxygen compared to ceria, implying the participation of bulk oxygen. Furthermore, on CexZr(1-x)O2 samples, oxygen is predominantly exchanged via a multiple heteroexchange mechanism involving surface dioxygen species as superoxides or peroxides.