ZrO2/TiO2 nanoparticles with various Zr/Ti ratios (0-0.9) were prepared by a polymer complex solution method (PCSM). The prepared samples were characterized using transmission electron microscopy (TEM), the Brunauer, Emmett & Teller (BET) method, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The ZrO2/TiO2 photocatalyst showed a high specific area and small crystal size. The XRD pattern for the Zr/Ti = 0.1 sample indicated that the addition of ZrO2 stabilized the anatase phase of TiO2 up to 800 degrees C. The photocatalytic activity of Zr/Ti = 0.1 sample was higher than that of the TiO2 sample and commercially available Degussa P25. The high photocatalytic activity can be attributed to stronger adsorption in the visible light region, higher specific area, smaller crystal size and increased surface OH groups. (C) 2009 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.