Usually, it is difficult to get small AgCl nanoparticles by a conventional aqueous solution route owing to their high nucleation and growth rate. In this study, AgCl nanoparticles with a diameter of less than 30 nm were uniformly coated on the surface of Ag8W4O16 nanorods to form Ag8W4O16/AgCl-nanoparticle core-shell heterostructures by a simple in situ anion-exchange route. It was found that the ion exchange reaction between Cl- and WO42- ions was preferable to occur on the surface of Ag8W4O16 nanorods rather than in the bulk solution, resulting in the formation of core-shell nanorods. The AgCl shell layer could be easily controlled by adjusting the concentration of NaCl solution. With increasing NaCl concentration, more Ag8W4O16 phase in the core transferred into AgCl-nanoparticle shell layer while the total size of the core-shell nanorods almost remained unchanged. The photocatalytic activity experiments of methyl orange aqueous solution under fluorescence light irradiation indicated that the AgCl nanoparticles coated on the surface of Ag8W4O16 nanorods, which could be readily separated from a slurry system after photocatalytic reaction, exhibited a much higher photocatalytic activity than the bulk AgCl photocatalyst. (C) 2010 Elsevier B.V. All rights reserved.