In this study, we evaluate the oxidation behavior of Incoloy 800HT with a view to its feasible application in the Gen IV supercritical water-cooled reactor. To evaluate the role of microstructure, we implement a specific thermo-mechanical treatment to process Incoloy 800HT. The processed samples were exposed to supercritical water for 100,300 and 1000 h. We found that the thermo-mechanical processing not only improves the oxidation resistance, but also alleviates the oxide scale spallation. The results demonstrated that in compare with texture, grain size has stronger effect on the oxidation resistance of Incoloy 800HT in supercritical water. (C) 2015 Elsevier B.V. All rights reserved.