A tensile stress test combined with an electrochemical polarization technique employing a molten salt as electrolyte, namely, a high-temperature straining electrode (HTSE) system, has been developed for study on the spalling and cracking characteristics of oxide films on metals and alloys. A 25 mol % K2SO4-25 mol % Na2SO4-50 mol % ZnSO4 melt was used at 773 K as the molten electrolyte and type 304 stainless steel (SS) as the specimen in this study. The SS was first polarized in a passive potential region in the molten sulfate mixture, and the anodic current during deformation at a constant strain rate was monitored. From both results of the current response and scanning electron microscope observation, it was confirmed that the current induced by spalling and cracking of oxide films was successfully monitored using the developed HTSE system. This system was also applicable for mechanistic study on anodic dissolution and subsequent passivation in the molten sulfates that occur immediately after the mechanical breakdown of oxide films. (C) 2004 The Electrochemical Society.