TaON-Ag nanocomposite thin films with Ag nano-particles embedded in TaON were prepared by reactive co-sputtering of Ta and Ag in the plasma of (O(2) + N(2))/Ar. The deposition temperature was either at room temperature or 300 degrees C. These films were characterized mainly by UV-Vis photometry and scanning electron microscopy. It is found that Ag doping into the TaON films leads to several beneficial changes on film properties. It would reduce the optical band gap and, therefore, enhance the films' photocatalytic behavior. It is also found that Ag nano-particles may emerge on the surface of TaON with or without RTA. This could be much meaningful since Ag particles' appearance is closely related to the antibacterial property of TaON-Ag films. The results show that TaON-Ag films deposited at 300 degrees C have an outstanding antibacterial behavior with the illumination of visible light due to the synergistic effects of Ag and photocatalytic behavior of TaON. (C) 2010 Elsevier B.V. All rights reserved.