Au nanoparticle doped Nb2O5 composite films (150 nm thickness) have been prepared by a liquid phase deposition method. The deposited films were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible (UV-vis) absorption spectroscopy. The mean sizes of Au particle varied from 7 to 10 nm after the heat treatment at 200-600 degreesC. The optical absorption spectra of these composite films demonstrated an absorption peak due to surface plasmon resonance of dispersed An nanoparticles. It was found that, with an increase in the heat treatment temperature, the wavelength of the surface plasmon resonance of the Au nanoparticles shifted from 577 to 595 nm. The peak shift of the plasmon band can be explained by the crystallization of Nb2O5 films. (C) 2003 Elsevier B.V. All rights reserved.