Photocatalysts Bi4Ti3-xCrxO12(x = 0.00, 0.06, 0.15, 0.30, 0.40, and 0.50) with perovskite structure were synthesized by sol-gel method and their electronic structures and photocatalytic activities were investigated. The Bi4Ti2.6Cr0.4O12 photocatalyst exhibited the highest performance of H-2 evolution in methanol aqueous solution (58.1 mu mol h(-1) g(-1)) under visible light irradiation (lambda > 400 nm) without a co-catalyst, whereas no H-2 evolution is observed for Bi4Ti3O12 under the same conditions. The UV-vis spectra indicated that the Bi4Ti2.6Cr0.4O12 had strong photoabsorption in the visible light region. The results of density functional theory (DFT) calculation illuminate that the conduction bands of Bi4Ti3O12 are mainly attributable to the Ti 3d + Bi 6p orbitals, and the valence bands are composed of 0 2p + Bi 6s hybrid orbitals, while the conduction bands of chromium-doped Bi4Ti3O12 are mainly attributable to the Ti 3d + Bi 2p + Cr 3d orbitals, and the 0 2p + Cr 3d hybrid obitals are the main contribution to the valence band. (C) 2009 Elsevier B.V. All rights reserved.