The spray pyrolysis technique was used to grow ZnO:Al films decorated with silver nanoparticles in their surface, in order to increase and stabilize the photocatalytic activity of ZnO. The appropriate amount of Ag nanoparticles was determined varying the concentration of an AgNO3 solution and the spraying time. The films were characterized by X-ray diffraction, scanning electron microscopy and energy dispersed spectroscopy. The photocatalytic activity of the films was evaluated by the degradation of a methyl orange dye solution. The stability of the photocatalytic activity was studied along five degradation cycles while exposed to simulated sunlight, white light and UV light. We found that a spraying time of 8 min of the AgNO3 solution gives nearly 3 at% of Ag in the ZnO:Al films. This amount of Ag nanoparticles stabilized the photoactivity under UV and sunlight along five degradation cycles, showing a synergistic effect between Al and Ag that greatly improved the photocatalytic performance of ZnO films. (C) 2013 Elsevier B.V. All rights reserved.