Inhibitive effect of Gossipium hirsutum L. leaves extract on the acid corrosion of aluminum in 1 M HCl solution was studied by weight loss technique. The extract at optimum concentration inhibited the corrosion of aluminum, with about 92% inhibition efficiency and the inhibition efficiency increased with increasing concentration of the extract at 30 oC. The results obtained revealed that the adsorption of the inhibitor molecule onto metal surface accords with Lanqmuir adsorption isotherm