A natural porous silica, pumice, was used as a substrate for photocatalytic TiO2. Mounting of anatase-typeTiO(2) was successfully performed through hydrolysis of TiOSO4 under hydrothermal conditions. Anatase-mounted pumice particles thus prepared were floating and rotating on the surface of water with stirring. Adsorption and photocatalytic performances were examined in methylene blue aqueous solution in the dark and under ultraviolet ray irradiation, respectively. Methylene blue in water could be decomposed rapidly by anatase-mounted on pumice particles. Their photoactivity was evaluated by subtracting adsorbed amount of methylene blue. High efficiency of usage of UV rays for photodecomposition of organic pollutants in water was expected. (C) 2004 Elsevier B.V. All rights reserved.