The analysis of Mentha rotundifolia L. essential oil by Gas Chromatography (GC) and Gas Chromatography-Mass 14 Spectrometry (GC/MS) allowed the identification of 25 components, which accounted for 94.3% of the total oil. 15 Pulegone (69.1%) and menthone (18.5%) were identified as main compounds. The inhibitive effect of this essential 16 oil on the corrosion of mild steel in 1M HCl solution has been investigated by weight loss measurement as well as 17 potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The gravimetric 18 results indicate that MR oil exhibits good inhibition efficiency in 1M HCl solution. The effect of temperature on the 19 corrosion behavior of mild steel was studied in the range of 303–333K. Polarization measurements showed that the 20 studied inhibitor is mixed type with significant reduction of cathodic and anodic current densities. Electrochemical 21 impedance spectroscopy measurements revealed that the charge transfer resistance increases with increase in the 22 concentration of essential oil. Various activation parameters such as activation energy, activation enthalpy and 23 activation entropy are evaluated and discussed. Adsorption thermodynamic parameters are also computed. 24 Linearity of Langmuir isotherm adsorptions indicated the monolayer formation of inhibitor on mild steel surface.
