The corrosion behavior of Alloy 800 in sulfate solutions containing hydrogen peroxide in the temperature range of 100-200 degrees C was studied. Electrochemical techniques were used to study both the cathodic and anodic processes. The reduction of hydrogen peroxide showed an increase in the steady state current density and the H2O2 diffusion coefficient by increasing the temperature from 100 to 200 degrees C. The electrochemical corrosion of Alloy 800 showed a decrease in corrosion potential and a decrease in transpassive potential in accordance with calculations for CrO4-2/Cr2O3 and HCrO4-/Cr2O3 couples. The increase in corrosion current density was compared with a predictive model based on both reaction kinetics and water property changes. The findings were compared with weight loss measurements and surface characterization studies. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.001303jes] All rights reserved.