Ag/TiO2 nanocomposite with various silver contents was synthesized by combination of sol-gel and the novel arc discharge methods in liquid. The Ag/TiO2 nanoparticles were characterized by X-Ray diffraction (XRD), Brunauer Emmett Teller (BET), transmission electron microscope (TEM) and ultra violet-visible absorption spectroscopy (UV-Vis). The visible light antibacterial activities and photocatalytic properties were successfully demonstrated for the inactivation of Escherichia coli (E-coli) bacteria and Rhodamine B (Rh. B). The results revealed that the Ag/TiO2 nanoparticles extended the light absorption spectrum toward the visible region and significantly enhanced the inactivation of E-coli bacteria under visible light irradiation. 0.15 gr Ag/TiO2 nanoparticles revealed best antibacterial activity while 0.05 gr Ag/TiO2 nanoparticles exhibited highest photocatalytic efficiency. The significant enhancement in the photocatalytic activity and antibacterial properties of Ag/TiO2 nanoparticles under visible light irradiation can be ascribed to the effect of noble metal Ag by acting as electron traps in TiO2 band gap. A mechanism for photocatalytic degradation of organic pollutants and antibacterial activity over Ag/TiO2 nanoparticles was proposed based on our observations. (C) 2011 Elsevier B.V. All rights reserved.