The objective of this work is study the carbonation of reinforced steel in different solutions include artificial seawater (3.5% NaCl), river water and domestic water by electrochemical method at room temperature. Corrosion parameters were measured to calculate corrosion rates from polarization curves. Cyclic polarization was tested to know the possibility of occurring for pitting corrosion. Both Tafel plot and cyclic polarization indicate that the corrosion of reinforced steel was the lowest in river water due to the impurities and clay in this water which can be inter to the pores in concrete and it does not allow to occur carbonation of reinforced steel in addition to forming calcium salts with anions in river water more than forming calcium carbonate which close the pores of concrete. The results were supplemented with optical microscopy.