TiO2, ZnO and ZnO/TiO2 thin films have been prepared by radio frequency magnetron sputtering method under different temperatures. Their photo catalytic activities have been investigated. The structural of the thin films were characterized by X-ray diffraction and Raman spectroscopy. The photo catalytic activities of TiO2 and ZnO/TiO2 samples were evaluated by the photo decomposition of methylene blue. We note that the structural proprieties of the thin films showed a perfect crystallization along the (002) for ZnO, Rutile (110) for TiO2 and Anatase (101) for TiO2. The experimental results show that the bilayer ZnO/TiO2 were the most efficient photo catalysts compared to the layer of TiO2. This increased catalytic effect can attributed to the interface between the ZnO layer and the TiO2 one, which modify significantly the chemical potential of the bilayer.