Abstract: Carboxymenthylchitosan(CM-chitosan) is an important and friendly environmental derivative.Inhibition of carboxymenthylchitosan the corrosion of aluminum in 1 mol/L HCl was investigated with gravimetric and electrochenical tests.The results reveal that this compound is a very good inhibitor and behaves better in 1 mol/L HCl solutions,and the highest efficiency of 88.54% is achieved when the concentration of the CM-chitosan is 200mg/L.In 1mol/L HCl solutions,the adsorption of CM-chitosan on the aluminum surface follows a modified Langmuir adsorption isotherm and some important thermodynamic parameters ΔGo,ΔHo and ΔSo are abtained.