Sn-doped and undoped nano-TiO2 particles have been synthesized by hydrotermal process without acid catalyst at 225 C in 1 h. Nanostructure-TiO2 based thin films, contain at different solid ratio of TiO2 in coating, have been prepared on glass surfaces by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, BET and UV/VIS/NIR techniques. The photocatalytic performance of the films was tested for degradation of malachite green dye in solution under UV and VIS-lights. The results showed that the hydrothermally synthesized nano-TiO2 particles are fully anatase crystalline form and are easily dispersed in water, the coated surfaces have nearly super-hydrophilic properties and, the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO2 thin film. The results also proved that malachite green is decomposed catalytically due to the pseudo first-order reaction kinetics. (c) 2007 Elsevier Ltd. All rights reserved.