Corrosion inhibition of aluminum i(1 M H₃ PO₄)n was investigated in absence and presence of Cydonia Vulgaris leaves (CVL) extracts as friendly corrosion inhibitors. The effect of temperature and inhibitor concentration at immersion time of (3h) was studied using weight loss method. The obtained results revealed that Cydonia Vulgaris leaves(CVL) extracts inhibited aluminum in (H₂ PO₄) and decreased the rate of corrosion. By increasing the concentration and temperature of the inhibitor, its efficiency increased. Higher inhibition efficiency for aluminum corrosion of (95.51%) was obtained at a higher level of inhibitor concentration and temperature. The adsorption of Cydonia Vulgaris leaves(CVL) extracts was found to obey Langmuir adsorption isotherm model. The values of the free energy of adsorption were more than (-20 kJ/mol) which was indicative of a mixed mode of physical and chemical adsorption. Activation enthalpy (∆H*), and activation entropy (∆S*) of aluminum corrosion was found to be (43.7254 kJ mol^(-1)), (-0.1804 kJ mol^(-1) K^(-1) ) and (20.2732 kJ mol^(-1)), (-0.1921 kJ mol^(-1) K^(-1)) in the absence and presence of the extract; respectively.