The corrosion inhibition characteristics of an imidazoline based inhibitor (IMI) on N80 and P110 pipeline steel in CO2-saturated simulated produced water and NaCl solutions was studied at pH 4 and at 25 40 and 60oC using electrochemical methods. IMI was found to inhibit the corrosion of the carbon steels in the solution to a maximum of 98.8% for N80 in the simulated produce water and over 99% in the NaCl solution for both N80 and P110. Inhibition efficiency shows no significant dependence on the range of IMI concentration studied but dependent on the composition of the metal and corrodent. A mixed-inhibition mechanism is proposed for the inhibitive effects of IMI.