The deposition of Na on thin film V2O5 has been study by using photoelectron spectroscopy. Vanadium ions are strongly reduced due to the deposition of Na. Three kinds of Na species were observed on the surface: the first is assigned to intercalated Na; the second is contributed to Na2O2; the third is appointed to metallic Na. The formation of Na2O2 leads to arise an emission line at about 10.3 eV in the valence band spectra. The metallic Na will further react with the oxides substrate and form Na2O2 on the surface in UHV chamber. (c) 2005 Elsevier B.V. All rights reserved.