The bipolar resistance switching in WO3+delta films sandwiched by Al and Pt electrodes was investigated by changing additional oxygen content (delta). Reliable switching voltages and retention were observed for all samples. As delta increases the bi-stable current voltage characteristics fluctuate leading to unstable switching power consumption. An analysis of the temperature dependence of the bi-stable resistance states revealed additional features that thermionic emission and metallic conduction co-contribute to the electrical transport of the resistance states. The authors propose that the observed resistance switching is due to the combined effects of potential modification near the interface and the formation of a metallic channel. (C) 2012 Elsevier B.V. All rights reserved.