The inhibition property of Ruta graveolens extract (RGE) on the corrosion of carbon steel in 1M HCl solution was investigated using potentiodynamic polarization and weight loss techniques. The percentage inhibition increased with the increase of the concentration of the extract. At a concentration of 2.0g/l, the percentage inhibition reached about 94.34% at 25℃ duration 6 hours. The inhibition efficiency decreased with the increase of temperature. The results showed that the adsorption of the extract on the carbon steel surface obeys Langmuir isotherm. Also the activation parameters, apparent activation energy (), the enthalpy of activation (∆) and entropy of activation (∆) for the corrosion of carbon steel in 1M HCl in the absence and presence of RGE were calculated and discussed. Ke