The ability of Cocos nucifera L. water (CW) as non-toxic corrosion inhibitor for acid corrosion of aluminium in 0.5 mol/L HC1 has been studied using chemical technique. CW shows significant inhibition as corrosion inhibitor, with 93% efficiency at the highest concentration of the inhibitor. The inhibitive action is attributed to the adsorption of the inhibitor molecules on metal surface following Langmuir adsorption isotherm.