Corrosion protection of zinc using Cnidoscolus Chayamansa leaves extract in natural sea water environment was studied by mass loss measurement with various period of contact and temperature. The observed result indicates that the corrosion inhibition efficiency was increased with increase of inhibitor concentration and temperature. The thermodynamic parameters viz; Ea, ΔHads, ΔGads, ΔSads were evaluated for corrosion process, which suggest that the adsorption is endothermic, spontaneous and chemisorptions. The inhibitor obeys both Langmuir and Temkin adsorption isotherm. The protective film formed on the metal surface was analyzed by using various spectroscopic studies viz; UV, FT-IR, XRD and SEM-EDX techniques.