Highly (100) oriented LaNiO3 films with different oxygen content were deposited on Si substrates by radio frequency sputtering and post-annealed in oxygen and vacuum conditions The formation of oxygen vacancies is directly observed by a decrease of lattice oxygen ratio in O 1s core-level photoelectron spectroscopy X-ray diffraction measurement indicates that low oxygen pressure during the deposition or annealing process has a significant influence on the lattice constant of LaNiO3 films Further valence band spectra and transport measurements demonstrate that the oxygen vacancies also have a significant influence on the electronic structure and transport behaviors of final LaNiO3 films (C) 2010 Elsevier B V All rights reserved