In this paper, thin bismuth oxide films were prepared by the sol-gel method. The films were annealed at different temperatures, and then applied to degrade a kind of typical textile industry pollutant (Rhodamine B), respectively, in order to study the influence of bismuth oxide crystal phases on their photocatalytic properties. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) techniques and a surface profiler were applied to characterize the thin films annealed at different temperatures. The results show that different annealed temperatures cause the transformation between monoclinic phase and tetragonal phase of bismuth oxides and bismuth oxide films annealed at 550 degrees C contain a higher proportion of the tetragonal phase of bismuth oxides than those annealed at other temperatures, which leads to higher electronic binding energy and photocatalytic properties for these oxides in the films. (c) 2006 Elsevier B.V. All rights reserved.