A sol–gel method was used to prepare Al–In co-doped TiO 2 photocatalyst. The materials were characterized by XRD, FT–IR, XPS, and N 2 adsorption–desorption measurements. Photocatalytic degradation of methyl orange on the materials was investigated. The diffraction peaks of all the samples are in accordance to the diffraction peaks of anatase phase TiO 2 . The addition of Al and In can lead to crystallite size shrinking of anatase TiO 2 in xAl–3%In–TiO 2 . The incorporation of Al 3+ ions into TiO 2 crystal are in the way of substituting Ti 4+ ions in anatase lattice. 0.5%Al–3%In–TiO 2 has the maximum specific surface area of 108.9m 2 /g and the smallest average pore size of 7.0nm. The aluminum doped xAl–3%In–TiO 2 materials have larger adsorption capacity than that of 3%In–TiO 2 . Total decoloration efficiency increases gradually with increasing Al content up to 0.5%, while 0.5%Al–3%In–TiO 2 has the maximal decoloration efficiency. 0.5%Al–3%In–TiO 2 also shows much improved activity as compared to 3%In–TiO 2 in each reuse cycle.