Nano-sized TiO2 particles have been formed by confined hydrolysis of Ti aqueous solution in silica sol-gel matrix. The method involves the formation of silica gel body as immobilizing host, and the following thermal hydrolysis of Ti aqueous solution as a function of time at 80 degreesC. Silica gel body was allowed to form in the mixed solution of silicic acid and Ti source at room temperature. The silicic acid was prepared by passing 5% sodium silicate solution into column of cation exchange resin, and Ti aqueous Solution was produced by slowly adding TiCl4 into the cold deionized water. The development of TiO2 nanoparticles in silica matrix was investigated by UV diffuse reflectance spectroscopy and XRD. It was observed that crystalline size of TiO2 was straightly increased during aging at 80 degreesC in free solution state, whereas almost constant in silica matrix. Nitrogen porosimetry for xerogel powders were carried out to study the effects of structural evolution caused by heating hydrogels. The interaction between SiO2 network and TiO2, and local environment was characterized by FT-IR and Si-29-NMR. (C) 2004 Elsevier B.V. All rights reserved.