An imidazoline-based inhibitor was synthesized, characterized and tested as a corrosion inhibitor for low alloy steel in CO2-saturated 3 wt.% NaCl solution at 60 degrees C. The influence of pre-corrosion on inhibition efficiency of the inhibitor was evaluated. The results showed that the inhibitor had excellent inhibition effectiveness on freshly abraded samples, with an inhibition efficiency of 98.7% in the presence of 2.4390 x 10(-5) mol/l inhibitor. The adsorption of the inhibitor on the steel surface was found to obey Langmuir's adsorption isotherm and chemisorption. Pre-corrosion had a detrimental effect on the inhibitor performance, significant localized corrosion was observed on the pre-corroded samples with 1.2195 x 10(-5) mol/l inhibitor after 96h immersion. The differences in inhibition efficiency of the inhibitor for samples pre-corroded for different time were related to the different corrosion products and the increase of surface area after pre-corrosion. (C) 2015 Elsevier B.V. All rights reserved.