Inhibition of corrosion of mild steel by Sulfonated melamine-formalin resin was investigated in Sulfuric acid medium (0.5 M) at various temperatures (303,313,323,333K) with the conventional weight loss, electrochemical polarization and electrochemical impedance spectroscopy (EIS). Weight loss method reveals good inhibition efficiency of the Sulfonated melamine-formalin resin and supports the data of electrochemical measurements. Polarization techniques substantiate the adsorption of inhibitor as a mode of inhibition. EIS technique shows the change in impedance parameters with change in concentration of inhibitor which corroborates the adsorption phenomenon resulting in the formation of a protective layer on the surface of mild steel. Adsorption of the inhibitor follows the Langmuir adsorption isotherm. Thermodynamic parameters like activation energy, free energy, enthalpy and entropy of the present system were obtained and elaborated. Based on all these evidences a suitable mechanism of the inhibitive action of the resin is proposed.
