The adsorption and inhibitive efficiency of Millingtonia hortensis leaves extract on mild steel in 1N HCl and 1N H2SO4 acid in the temperature range (303 to 343k) are investigated by mass loss measurements. The value of inhibition efficiency increased with increase of inhibitor concentration and decreased at 333K. ΔGads adsorption value in the range 12 – 24 KJ / mol is suggestive of physisorption processs. Adsorption of inhibitor on the metal surface was found to obey Langmuir and Temkin adsorption isotherm. The values of activation energy (ΔEa), free energy of adsorption (ΔGads), enthalpy of adsorption (ΔH) and entropy of adsorption (ΔS) were calculated.