Majority of the authors report elaboration of iron oxide thin films by reactive magnetron sputtering from an iron target with Ar-O 2 gas mixture. Instead of using the reactive sputtering of a metallic target we report here the preparation of Fe 1-x O thin films, directly sputtered from a magnetite target in a pure argon gas flow with a bias power applied. This oxide is generally obtained at very low partial oxygen pressure and high temperature. We showed that bias sputtering which can be controlled very easily can lead to reducing conditions during deposition of oxide thin film on simple glass substrates. The proportion of wustite was directly adjusted by modifying the power of the substrate polarization. Atomic force microscopy was used to observe these nanostructured layers. Mössbauer measurements and electrical properties versus bias polarization and annealing temperature are also reported.