Electron spectroscopy has been used to investigate the oxidation and the post-annealing behaviors of a Pr/Si surface. The Pr overlayer with a thickness of about 20 Angstrom was deposited on Si(1 0 0) at room temperature. It was found that some of the Pr atoms form chemical bonds with Si. An initial fast oxygen adsorption on the Pr/Si surface is mainly associated with the formation of Pr2O3. The presence of praseodymium enhances the oxidation rate of the substrate. The silicon atoms diffuse from the Pr-Si bonds as well as the substrate into the Pr2O3 layer, forming a Pr-O-Si silicate. SiO2 was also observed during oxygen adsorption, which was caused by the oxidation of the Pr-O-Si silicate in the vicinity of the top surface. At high oxygen exposures, a slow further oxygen uptake is related to the growth of the Pr-O-Si bond and SiO2. Both Pr2O3 and SiO2 decrease in intensity while the Pr silicate grows with annealing temperature. (C) 2003 Elsevier B.V. All rights reserved.