The corrosion inhibition of aluminium in 1 M HCl solution by Morinda citrifolia L. (M. citrifolia L.) using chemical (weight loss, gasometry) and electrochemical (ac impedance and polarisation) techniques. All the methods employed are in quite good agreement. The inhibition efficiency increased as M. citrifolia L. concentration increased. It was found that adsorption for M. citrifolia L. on aluminium obeys with Langmuir adsorption isotherm in all studied temperature. Thermodynamic parameters (ΔGads, ΔHads and ΔSads) for M. citrifolia L. adsorption on aluminium were found out and discussed at each temperature.