Abstract: In this work, the extract of Allium Sativum was examined as a green corrosion inhibitor for zinc in 0.5N H2SO4 by using weight loss, gasometric and thermometric methods. Results indicated that the extract of Allium Sativum performed as a very good corrosion inhibitor for the corrosion of zinc. The inhibition efficiency increases with the increase in the extract concentration. The adsorption of the inhibitor molecules on the zinc metal surface obeyed Temkin adsorption isotherm.