Zirconium ions (Zr4+)-doped titanium dioxide (TiO2) nanocrystal was prepared by sol-gel method. The structure and surface morphology of the samples were characterized by X-ray diffraction (XRD), infra-red (IR) spectra and transmission electron microscopy (TEM), and moreover the specific surface area of the samples was investigated by Brunauer-Emett-Teller (BET) method. The photocatalytic efficiency and the anti-inactivation stability of pure and doped TiO2 was tested by decolorizing methyl orange and degrading nitrobenzene solution. The results showed that low-amount presence of Zr4+ could suppress the growth of TiO2 grains, raise the surface area, and accelerate surface hydroxylation, which resulted in the higher photocatalytic activity of the doped TiO2. The first degradation results of doped samples were all higher than pure TiO2 and TiO2 Degussa P-25, and when the Zr4+ content was 6 mol%, the photocatalytic efficiency of Ti0.94Zr0.06O2 was 1.5 times as high as that of pure TiO2 investigated by spectrophotometry and gas chromatography; however the Degussa P-25 presented the highest anti-inactivation stability. (C) 2004 Elsevier B.V. All rights reserved.