By using sol-gel method, amorphous titania was introduced into epoxy matrix to prepare a series of high refractive index TiO2/epoxy resin nanocomposite films. To increase the refractive index of the hybrid films, triethoxysilane-capped trimercaptothioethylamine (TCTMTEA), a new kind of high refractive index coupling agent was synthesized from trimercaptothioethylamine (TMTEA). In the experiment, TCTMTEA acted as the solidification agent together with TMTEA except being used as the coupling agent. The hybrid films have been characterized via FTIR, AFM, DSC, TGA, etc. The experimental results showed that the amorphous TiO2 had been dispersed uniformly in the organic polymer matrix with the size smaller than 100 nm in each sample. More importantly, the refractive index of this kind of materials can be continuously adjusted from 1.61 to 1.797 with the content of TiO2 increasing from 0% to 65% in mass, and the continuously adjusted refractive index is very important for the applications in optical antirefractive films. (c) 2006 Wiley Periodicals, Inc.