Firing processes of sol-gel-derived titania gel films were investigated by temperature programmed desorption (TPD), X-ray diffraction and X-ray photoelectron spectroscopy (XPS). Two kinds of gel films (T-1 and T-2) were prepared from Ti(OC2H5)(4) and TiCl4 as titanium sources, respectively. TPD results for both types of film showed different TPD curves depending on the titanium sources, indicating that the components in the gel films and their firing processes differed corresponding to the starting materials. The amounts of the evolved species were calculated on the basis of the TPD and XPS data. The Ti/O ratio in the titania gel films was estimated by analyzing the XPS and TPD results. These experiments also revealed that the crystallization temperature of the gel films corresponded to their components and Ti/O ratio. (C) 2004 Elsevier B.V. All rights reserved.