Oil of Melia azedarach seeds (MA-oil) was extracted and modified in the form of amido poly amine surfactant (MA-amido surfactant). The surface active properties of the new MA-amido surfactant were performed. Corrosion inhibition of C- steel in 2.0 M HCl by MA-amido surfactant was investigated using weight loss (WL), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). The results indicated that the corrosion of C- steel was obviously reduced. Potentiodynamic polarization curves showed that the MA- amido surfactant behaves as a mixed type inhibitor. The adsorption process at the C-steel surface obeys Langmuir adsorption isotherm model. The activation and thermodynamic parameters of the adsorption were evaluated and discussed. The protective film at the metal surface was characterized by SEM.