A study of monopropianate (N-Coco alkyl aminopropionic acid) as a corrosion inhibitor for carbon steel in 0.5M HCl has been carried out by using weight loss and electrochemical tests, namely potentiodynamic polarization curves and electrochemical impedance spectroscopy at 25, 40 and 60°C. Results have shown that monopropianate is a good inhibitor for the corrosion of 1018 carbon steel in this acidic environment. Inhibitor efficiency increases with increasing the inhibitor concentration but decreases with an increase in the testing temperature. Inhibitor efficiency increases with time at 25 °C but at higher temperatures it decreases. This is explained in terms of corrosion process control and inhibitor adsorption isotherm.