The aim of this paper is an investigation of the photocatalytic efficiency of TiO (x) thin films deposited by DC reactive magnetron sputtering at low temperature and doped by Ag noble metal. Crystallographic structure and chemical composition of as-deposited films were examined by XRD and RBS, respectively. Ag/TiO (x) films morphology was studied by SEM analysis. The photocatalytic activity was evaluated from the decomposition speed of an aqueous solution of the Acid Orange 7, exposed to UV/VIS light. A systematic change of Ag concentration in TiO (x) films led to a maximum activity. Such a maximum is discussed taking into account composition, morphology and structure of the films.