Effect of Eugenia Singampattiana Beddome leaves extract on erosion of mild steel in Natural ocean water was researched by Mass loss and Electrochemical measures with various period of contact and temperature. The observed results indicate that the erosion inhibition effectiveness was increased with increase of inhibitor concentration but dropped gradationally with rise in temperature effect of “Eugenia Singampattiana Beddome” leaves extract on erosion of mildsteel in Natural sea water was researched by mass loss and electrochemical measures with various period of contact and temperature.The observed results indicate that the erosion inhibition effectiveness was increased with increase of inhibitor concentration but dropped gradationally with rise in temperature.The highest possibility of inhibitory effectiveness was 95.24 %. For the erosion process, the thermodynamic parameters (Ea, ΔHads, ΔSads) were calculated, which suggests that the adsorption is exothermic, spontaneous, and Physisorption. The Langmuir adsorption isotherm is followed by the inhibitor. (The average coefficient of regression is 0.9917) Various spectroscopic research, FT-IR, EDX, and XRD techniques were used to examine the corrosion products created on the metal surface, and the film production was also validated by SEM picture. The maximum chance of inhibition effectiveness attained 95.24%. The thermodynamic parameters (viz; Ea,ΔHads, ΔSads) were estimated for erosion process, which may suggested that the adsorption is endothermic, spontaneous and Physisorption. The inhibitor follows Langmuir adsorption isotherm. (The average Regression Coefficient value 0.9917) The corrosion products formed on the metal surface was analyzed by using various spectroscopic studies FT-IR, EDX and XRD techniques and the film formation also confirmed by SEM image