Ag@TiO2 core-shell-type nanophotocatalysts have been prepared using a simple and convenient method. The products were characterized by TEM, XRD, and UV-vis spectra. To make the catalysts achieve the highest photocatalytic activity under UV light illumination, the Ag content of Ag@TiO2 was optimized. The results showed that Ag@TiO2-doped Fe3+ extend their absorption into the visible region. Among the Fe3+-doped samples, Ag@Fe-TiO2 with low Ag content showed higher photocatalytic activity under visible light illumination. An excessive added amount of Ag would reduce Fe3+ to Fe2+ and make them difficult to be incorporated into the lattice of titania. From the experiments, we found that Fe3+ ions could stabilize the Ag@TiO2 colloid by holding back the aggregation of the core-shell nanoparticles. (C) 2008 Elsevier Inc. All rights reserved.