The inhibitive action of plant leaf extracts, Crataegus oxyacantha (Hawthorn) and Prunus Avium (Sweet Cherry) on the corrosion of mild steel in 0.5 M HCl solution was investigated using open circuit potential-time measurements (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Functional groups of these plants' leaf extracts and their absorption bands were identified by Fourier transform infrared spectroscopy (FTIR) and Ultra-Violet Spectrophotometer (UV), respectively. The leaf extracts showed good inhibition efficiency in hydrochloric acid solution. Potentiodynamic polarization curves revealed that Crataegus oxyacantha and Purnus Avium plants leaves extracts acted as mixed type inhibitors. Theoretical fitting of different isotherms, Langmuir, Florry-Huggins and the kinetic-thermodynamic models was tested to describe the mode of inhibitors' adsorption on mild steel surface. UV spectra proved that the inhibiting action takes place through simple physical adsorption of the extracts molecules on mild steel surface.

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