The resin was prepared by the method of polymerization of complex, this method uses in situ polymerization, soluble metal polymerisation compounds are prepared with citric acid, and only AbstractThe TiO 2 /In 2 O 3 thin films were prepared by the spin coating method, varying their number of layers (4, 8 and 16 layers). The Method of polymerization of complex (CPM) was used to synthesize the precursor resins in order to produce thin films. The TiO 2 /In 2 O 3 films were heat-treated at 300°C, 500°C and 700°C and characterized by X-ray diffraction, scanning electron microscopy (FEG-SEM), atomic force microscopy (AFM), UV-vis spectrophotometer and photoluminescence (PL). It was found that the band gap energy of the as-prepared TiO 2 /In 2 O 3 composite thin films decrease as temperature increases. According to the UV-vis diffuse reflectance spectra, the TiO 2 /In 2 O 3 composite shows good visible-light absorption ability. The photoluminescent properties of the films were studied at room temperature using a wavelength of 350nm excitation. High photoluminescent intensity was observed for the films treated at 300°C heat, studied in different films. The photocatalytic activity of the composite TiO 2 /In 2 O 3 was evaluated by the photodecomposition of methylene blue dye in aqueous solution and showed that all the composite samples presented excellent photocatalytic performance even when recycled. This study shows that the coupling of TiO 2 with In 2 O 3 is an effective way to increase the TiO 2 absorption in the visible region for catalytic applications and that the temperature has a greater influence on the results than the number of layers.