Electrochemical techniques are practical and powerful for monitoring the corrosion process of rebar in the concrete. A brief review of electrochemical techniques used in the concrete industry is given in this paper. The corrosion process of rebar in the concrete with the immersion time in NaCl solution was studied with Linear Polarization Resistance (LPR) technique and Electrochemical Impedance Spectroscopy (EIS). Polarization resistance of rebar with both LPR and EIS techniques exhibits a good agreement.