As an excellent optical or photoelectric material, indium tin oxide (ITO) film was prepared by sol-gel dip-coating and subsequent annealing process. X-ray reflectivity measurement based on the first Born approximation theory was performed for the characterization of surface roughness of ITO film. It is found that the roughness can be described as self-affined over finite length scales and the surface roughness increases with the annealing temperature or holding time. The results were compared with complementary data obtained by atomic force microscope tests and it is found that they match very well. The first Born approximation theory provides a valuable tool for the rough surface characterization of sol-gel films/coating through X-ray reflectivity technique. (C) 2009 Elsevier B. V. All rights reserved.