The inhibitive nature of alcoholic extract of Mimusops elengi leaves (MEL) extract on Copper in Natural Sea Water is investigated by mass loss measurement with various contact period and temperature. The observed results suggest that the percentage of inhibition efficiency is increased with increase of inhibitor concentration. The maximum % of inhibition efficiency is attained at 86.84% after 120 hours exposure time. In temperature studies, the adsorption of inhibitor on the metal surface follows the mechanism of chemical adsorption. The calculated values of ∆Hads and ∆Gads suggest that the adsorption may be endothermic and spontaneous process. The inhibitor obeys Langmuir adsorption isotherm. The protective film formed on the metal surface in the presence and absence of inhibitor is analysed by UV, FT-IR, EDX and SEM spectral studies.