The TiO 2-SiO 2 thin film was prepared by self-assembly method by mixing SiO 2 precursor with titanium precursor solution and aged to obtain a co-precipitation of silica and titanium crystals. Dip coating method was applied for thin film preparation on glass slide. The X-ray diffraction (XRD) of the self-assembly thin film had no characteristic property of SiO 2 and even anatase TiO 2 but indicated new crystal structure which was determined from the Fourier Transform Infrared Spectrophotometer (FTIR) as a hybridized Ti-O-Si bonding. The surface area and surface volume of the self-assembly sample were increased when SiO 2 was incorporated into the film. The self-assembly TiO 2-SiO 2 thin film exhibited the enhanced photocatalytic decolorization of methylene blue (MB) dye. The advantages of SiO 2 are; (1) to increase the adsorbability of the film and (2) to provide the hydroxyl radical to promote the photocatalytic reaction. The self-assembly thin film with the optimum molar ratio (SiO 2:TiO 2) as 20:80 gave the best performance for photocatalytic decolorization of MB dye with the overall efficiency of 81%.© 2011 Elsevier Ltd. All rights reserved.