The corrosion inhibition performance of imidazoline derivative (IM) and l-cysteine (CYS) on carbonsteel in CO2-saturated brine solution was investigated by potentiodynamic polarization, electrochemi-cal impedance spectroscopy (EIS), weight loss, contact angle and X-ray photoelectron spectroscopy (XPS)measurements. The results show that the inhibition performance of individual IM is slight for CO2inducedcorrosion, and can be strengthened greatly by combined use with Cys. The synergistic inhibition effectof IM and CYS is observed. An adsorption model involving the initial adsorption of CYS on carbon steelsurface followed by IM was proposed to elucidate the synergistic mechani**.