Nanosized　porous　In(OH)3　photocatalysts　with　high　surface　areas　(as　much　as　110　m2g-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,andtoluene)　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　In2O3　and　TiO2.　One,　therefore,　can　conclude　that　nanosized　In(OH)3　has　potential　application　in　environmental　treatment,　especially　in　the　removal　of　benzenecontaining　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.　©　2010　American　Chemical　Society.