Doped indium-TiO2 mesoporous photocatalysts were synthesized by a controlled sol-gel process. The catalysts were characterized by XRD, N-2 physisorption, UV-Vis-DRS, Photoluminescence and Raman spectroscopies. The indium-TiO2 semiconductors were immobilized on perlite granules by a simple coating method and examined by SEM-EDS. Photocatalytic activity of the In-TiO2/perlite materials was evaluated by the decomposition of ethylbenzene in moist air in a plug-flow photoreactor with a concentric cylindrical configuration, under 254 or 365 nm irradiation. Ethylbenzene was substantially decomposed by oxidation in an air steam flowing over the In-doped coated/perlite granules. The decomposition rate of ethylbenzene may be attributed to the presence of indium, which can increase surface phenomena and sensitize the response of the semiconductors to the 365 nm UV irradiation. The materials with indium content show enhanced decomposition rates in contrast to the undoped materials. The study indicates that the immobilized In-TiO2/perlite photocatalysts may be a practical way to decompose volatile organic compounds in a stream of moist gas. (C) 2013 Elsevier B.V. All rights reserved.