Bismuth titanate Bi4Ti3O12 was prepared by using the chemical solution decomposition (CSD) method. The obtained powders were characterized by X-ray diffraction (XRD), UV-Vis spectroscopy. Photocatalytic property of Bi4Ti3O12 crystals was evaluated by using methyl orange as a model organic compound. The factors affecting the photocatalytic activity, such as calcination condition for the photocatalyst, the pH value of the reaction suspension, the strong oxidant species additives H2O2 and the addition of NaCl, NaNO3 and K2SO4 into the suspension, have been studied. The band gap energy value for Bi4Ti3O12 compound is 3.08 eV observed by a UV-Vis recording spectrophotometer. Bi4Ti3O12 exhibits photocatalytic activities to photodegrade methyl orange. The bond angle of Ti-O-Ti in Bi4Ti3O12 and the formed intra-electric field between the (Bi2O2)(2+) layer and the (Bi2Ti3O10)(2-) layer are assumed to motivate the separation of the photogenerated electrons-holes pairs and then improve the photocatalytic activity of the catalysts. (C) 2004 Elsevier B.V. All rights reserved.