In this paper, the heterostructure In2O3/In(OH)(3) photocatalyst was prepared by programmed thermal treatment of In(OH)3 using In2O3/In(OH)(3)center dot 9H(2)O as the precursor. Various characterization methods such as X-ray power diffraction (XRD). UV-vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectrometry (FT-IR) and transmission electron microscopy (TEM) were employed to investigate the structure, morphologies, and optical properties. Terephthalic acid was used as a probe molecule to detect the generation of hydroxyl radicals ((OH)-O-center dot) on the surface of UV-illuminated photocatalyst by a photoluminescence (PL) technique. The results showed that the photocatalytic activity of the heterostructure In2O3/In(OH)(3) was higher than that of single In2O3 or In(OH)(3). The increased photocatalytic activity may be attributed to the formation of the heterojunction between In2O3 and In(OH)(3), which suppresses the recombination of photoexcited electrons-hole pairs. (C) 2010 Elsevier B.V. All rights reserved.