Directorate for Nuclear Safety and Security 1 article published in JoVE Chemistry U2O5 Film Preparation via UO2 Deposition by Direct Current Sputtering and Successive Oxidation and Reduction with Atomic Oxygen and Atomic Hydrogen Thomas Gouder1, Frank Huber1, Rachel Eloirdi1, Roberto Caciuffo1 1European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security This protocol presents the preparation of U2O5 thin films obtained in situ under ultra-high vacuum. The process involves oxidation and reduction of UO2 films with atomic oxygen and atomic hydrogen, respectively.