Corrosion behaviour of two carbon steel alloys used in the production and transportation of oil were investigated to evaluate their corrosion behaviour in CO2 – saturated solution, as function of chloride ions content, at ambient temperature and pressure. The study used electrochemical measurements including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Both alloys showed a peak value at 3.5 Wt. % NaCl, followed by a drop on further chloride ion increase up to 15 Wt. % NaCl. Nevertheless Alloy2 showed a much better performance and lower corrosion rate which could be related to composition, grain size and mechanical properties. Reduction in corrosion rates in spite of further addition of chloride ions was explained on the basis of reduction of CO2 solubility or salting out and the role of chloride ions in accelerating iron dissolution which are available then adsorbed through the electrolyte to the cathodic sites, reducing active sites on the substrate for further reduction of carbonic acid and bicarbonate.