The inhibition effect of methionine on the corrosion behaviour of copper was investigated in 3.5% NaCl solution with and without methionine. For this purpose, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) techniques were used. The surface morphology of the metal surface after exposed to corrosive medium was investigated by scanning electron microscopy (SEM). The effect of temperature has also studied in the temperature range from 298 K to 328 K. The effect of temperature has also studied in the temperature range from 298 K to 328 K. Some thermodynamic parameters were calculated and discussed. It was found that, methionine could inhibit the corrosion of copper in 3.5% NaCl solution. Methionine as a organic corrosion inhibitor for copper, and physically adsorbed molecules forming a protective film. Inhibition efficiency increases with decreasing methionine concentration and behaves as a mixed-type inhibitor.