Alloy 800 is one of the potential steel alloys to be used in the cooling system of the next generation of power plants. The corrosion behavior of the alloy is dominated by its passive film. The kinetics of passive film growth is the subject of this study. Long-term open circuit potential tests, along with polarization resistance and electrochemical impedance spectroscopy tests provide data on evolution of passive state on the metal surface. It shows that the metal would possibly be in the active region after 24 h of immersion in the absence of hydrogen peroxide while the alloy undergoes the active-passive transition in solution containing 10(-4) M hydrogen peroxide. Polarization resistance data showed that the passive film continues thickening after OCP stabilization in the case of presence of H(2)O(2). EIS data generally confirms the overall RI, behavior. The time-dependent EIS models were used for more in-depth evaluation of passive film kinetics. (C) 2011 Elsevier Ltd. All rights reserved.