The effect of aqueous extract of leaves of Morinda tinctoria on the corrosion inhibition of copper in 0.5 M hydrochloric acid was studied using weight loss and electrochemical techniques. Results obtained from weight loss data indicate that the extract is effective in hydrochloric acid medium and the efficiency increases with an increase in the exposure time. The increase in temperature and acid concentration decreases the inhibitor efficiency. The data for the adsorption of extract fit well with Freundlich isotherm. The AC impedance studies reveal that the process of inhibition is through charge transfer reaction. (C) 2014 Elsevier B.V. All rights reserved.