The corrosion behavior of type 310S stainless steel was studied in the eutectic Li+K carbonate as a function of temperature by several electrochemical methods. Within the range 600-675 degrees C the steel passivated spontaneously at OCP condition after a few hours of immersion. Active-passive transition was observed in the polarization curves below 600 degrees C and above 675 degrees C indicating a failure to reach a stable passive condition even at prolonged exposure times. Impedance analysis indicates that passivity does not lead to the formation of an impervious barrier layer as denoted by the presence of diffusional components at low frequencies indicating oxide growth. Corrosion rates exhibited a minimum at 675 degrees C at both OCP and at cathode polarization conditions. A mechanism to explain the active-passive transition has been proposed based on the phase transition from LiFe5O8 to LiFeO2. (c) 2006 Elsevier B.V. All rights reserved.