The Pt-SnO2 system has attracted much attention as catalysts and gas sensors. Reduction-oxidation treatment has been reported to significantly affect the microstructure and activity of SnO2-supported platinum (Pt/SnO2) catalyst. In this study, the electrochemical property of Pt-SnOx device was investigated. This device repeatedly exhibited ohmic and rectifying characteristics in response to reduction and oxidation treatments, respectively. The ohmic behavior was also confirmed under reducing conditions, while the rectifying effect of this device appeared in a gaseous mixture of 5% CO-15% O-2-80% N-2. These electrochemical phenomena could be explained by the adsorption of gaseous species and the diffusion of atoms and ions to constituent materials. (C) 2015 Elsevier B.V. All rights reserved.