Nanosized porous In(OH)(3) photocatalysts with high surface areas (as much as 110 m(2)*g(-1)) were successfully synthesized by peptization of colloidal precipitates under ultrasound radiation. The resulting catalysts were characterized by X-ray powder diffraction (XRD), thermogravimetric analysis, nitrogen adsorption, transition electron microscopy, and UV-vis diffuse reflection spectroscopy. The photocatalytic activities of the samples were evaluated by the gas-phase decomposition of several volatile organic pollutants (acetone, benzene, and toluene) under UV light illumination and were compared with that of the commercial titania (Degussa P25). Results revealed that the as-synthesized In(OH)(3) exhibited much higher photocatalytic activity and durability than both In(2)O(3) and TiO(2). One, therefore, can conclude that nanosized In(OH)(3) has potential application in environmental treatment, especially in the removal of benzene-containing exhaust emissions from shoemaking plants in China. The excellent photocatalytic performance of In(OH)(3) can be attributed to its strong oxidation capability, abundant surface hydroxyl groups, and high BET surface area as well as the porous texture.