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The influence of calcination and redox cycles on the structural modification and redox properties of a ceria–zirconia mixed oxide of nominal composition Ce_0.6Zr_0.4O₂ were investigated by XRD and Rietveld refinement, by BET measurement, TPR and OSC analyses. The material is characterized by high total OSC and retains this property after several redox and calcination cycles up to 1273K, despite the loss of porosity and the decrease of surface area. The Rietveld analysis of the diffractograms allowed to establish that at least two solid solutions are present in the as-prepared sample: a cubic phase, space group Fm-3m, richer in cerium compared to the nominal composition, a tetragonal phase (t′) richer in zirconium. The first redox treatment modifies the composition towards two different solid solutions with composition closer to the nominal one: a cubic Ce_0.65Zr_0.35O₂ and a tetragonal (t′) Ce_0.47Zr_0.53O₂ …