The role of hydroxyl group in cerium hydroxycinnamate compounds has been studied as an effective corrosion inhibitor for mild steel in 0.6 M chloride solution. The results show that the surfaces of mild steel coupons exposed to solutions containing inhibitors had no signs of corrosion attack due to protective film formation, whereas the surface of mild steel coupons exposed to non-inhibitor containing solutions was severely corroded. Cerium hydroxycinnamate compounds showed as a better inhibitor for AS1020 steel at higher concentration. The addition of Cerium hydroxycinnamate compounds form protective film layer and improves the protective film and charge transfer resistance which plays an importance role in corrosion properties. A high inhibition performance is attributed to the forming protective inhibiting deposits that slow down the electrochemical corrosion reactions. The results also indicated that the position of hydroxyl group in cerium hydroxycinnamate significantly effect to the inhibition performance of mild steel in chloride ion media.