Fe and Fe3O4 thin films were grown by radio frequency magnetron sputtering. Fe2O3 was used as the target and hydrogen was introduced together with Argon gas to provide a certain reducing atmosphere. By varying H-2/Ar flow ratio, the changes in composition and structure of the thin films from (110) Fe to (111) Fe3O4 were observed by X-ray diffraction. The valence states of Fe in the thin films were analyzed by X-ray photoelectron spectroscopy. Magnetization measurements indicate that the Fe thin films grown with low H-2/Ar flow ratios possess large coercive force. It was ascribed to the increasing boundary density and the increasing amount of Fe oxides such as FeO distributed at the boundary. (c) 2011 Elsevier BM. All rights reserved.