CuO x-CeO 2-δ /Si thin films were elaborated by pulsed laser deposition. At the surface of all CuO x-CeO 2-δ thin films, Ce 4+ and Cu +1 ions were present. Depth profiles indicated that a Cu 2 O rich layer, roughly 40 nm thick, covered the CuO x-CeO 2−δ thin films. Apart from the copper enriched surface, the copper repartition in the thin films is highly inhomogeneous and two types of copper oxides, CuO and Cu 2 O, in form of rounded grains 20 nm were identified in the thin films. At least 10 at. % Cu seems to be inserted in the ceria lattice. Pure CeO 2 grains result from the deposition of tetrahedron-like nanoclusters followed by coalescence of (111) faces, and CuO x-CeO 2-δ grains from the deposition of cube-like nanoclusters followed by coalescence of (110) faces. The good catalytic performances of the CuO x-CeO 2-δ /Si thin films are due to active {100} ceria exposed facets covered by a Cu 2 O nanoparticles.