The inhibitive action of the extracts of three green inhibitors namely Adathoda vasica, Eclipta alba and Centella asiatica were investigated. Polarization method indicates that the plant extracts are under mixed control i.e promoting retardation of both anodic and cathodic reactions. The impedance method reveals that charge-transfer process controls the corrosion of mild steel. The plant-extracts obeys Langmuir adsorption isotherm. Kinetics and reason for the corrosion inhibition or the nature of adsorption is clearly shown. Physisorption mechanism has been proposed for the inhibition action of these plant extracts. The protective film formed on the surface was confirmed by Scanning Electron Microscopy (SEM). From hydrogen permeation method, all the plant extracts were able to reduce the permeation current. Results obtained in all the methods are very much in good agreement with increasing inhibition efficiency in the order: Eclipta alba > Adathoda vasica > Centella asiatica. Among the three plant extracts studied, the maximum inhibition efficiency was found in Eclipta alba which showed 99.6% inhibition efficiency at 8.0 % v/v concentration of the extract.