Bismuth oxide films were deposited onto quartz substrates by radio frequency reactive magnetron sputtering using a bismuth metal target. The substrate temperature was varied from room temperature to 500 degrees C. The state of Bi ions in the deposited films was characterized by XPS and the results showed that Bi ions existed as Bi3+ ions. The film structure was characterized by XRD and Raman scattering. The film deposited at room temperature shown a delta-phase predominant amorphous structure. As the substrate temperature was higher than 300 degrees C, polycrystalline structure was formed. The film optical properties were studied by measuring the transmittance. The optical band gap was estimated by the Tauc plot, showing a red shift with the increase of the substrate temperature which gives it a potential application as a photocatalytic material for visible light. (C) 2018 Elsevier B.V. All rights reserved.