The characteristics of reactivation polarization behavior of Alloy 600 in 0.5 M H2SO4 + 0.005 M KSCN solution were investigated. The feasibility of single-loop electrochemical potentiokinetic reactivation (SL-EPR) test technique for the evaluation of the degree of sensitization (DOS) was also explored. The experimental results showed that both sensitized and unsensitized materials exhibited reactivation curves with two separated anodic peaks. The results of reactivation termination tests showed that the anodic peak which appeared at -50 mV (SCE) was associated with the depassivation of grain matrix, while that at + 100 mV (SCE) was corresponding to the grain boundary corrosion for sensitized Alloy 600. The anodic peak at more noble potential in the EPR curve might also reflect the occurrence of pitting corrosion of Alloy 600 in the testing electrolyte.