CeO2- and CeO0.63Zr0.37O2-supported noble metal catalysts were studied. Samples were fully characterized using TEM, XRD, N-2 adsorption and H-2 chemisorption. The oxygen storage process was investigated focusing on the evolution as a function of temperature of both the oxygen storage capacity (OSC) and the oxygen storage complete capacity (OSCC). Aging effect on OSC was also examined in details in the case of Rh catalysts. Finally, the major role of oxygen diffusion, partly influenced by the metal/support interface quality, was confirmed.