Molybdenum deposition on the thin alumina film was investigated by HREELS, XPS and UPS. HREELS and XPS results show that a strong interaction occurs between the molybdenum and the oxide, and the electron transfers from the metallic nanoparticles to the underlying substrate. UPS measurements demonstrate that the Mo 4d valence band edge of the metallic nanoparticles locates at 1.36 eV, far below the Fermi level of the bulk molybdenum. This unique electronic structure of the metallic nanoparticles may provide a totally different property from the corresponding bulk materials, indicating a significant nanometer size effect. (C) 2007 Elsevier B.V. All rights reserved.