Abstract: Electrochemical characteristics of steel mortar samples with and without electrochemical chloride extraction treatment are measured by using half cell potential method, galvanostatic transient response and AC impedance techniques. Measured results show that the steel's potential becomes positive, and that the product of resistance and capacitance ( RC ), and the transmission resistance also increase after electrochemical chloride extraction treatment. It can be seen that the electrochemical chloride extraction treatment makes the steel bar from active to passive.