Bi4Ti3O12 thin films with bismuth-layered perovskite structure have been successfully fabricated by means of chemical solution decomposition (CSD) and characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and UV-vis spectrophotometry in this study. The photocatalytic activity of Bi4Ti3O12 thin films has been evaluated by photodegrading methyl orange solution, and the optimum processing parameters for the photocatalytic activity have been found. Moreover, it has been found that La-doping can improve the photocatalytic activity of Bi4Ti3O12 thin films and hinder the increase of crystallite sizes during calcination. (C) 2008 Elsevier B.V. All rights reserved.