In this work potentiostatic study for the corrosion inhibition of carbon steel(C.S) was studied in saline water using hot water extracted of Olive using four extracted concentrations (1, 2, 3 and 4 ppm) at temperatures range 298-328K. Inhibition efficiency I% results show that all chooses concentrations gave about I% 99%. Thermodynamic functions of corrosion processes were calculated from experimental polarization data and the interpretation of the results reveals that Olive extract obey Langmuir adsorption isotherm. Polarization curves indicate that Olive extract act as anodic - type inhibitor at low concentration and cathodic - type inhibitor at higher concentration. The small values of the equilibrium constant of the adsorption-desorption process Kads refer to physical adsorption process. The values of free energy of adsorption ÄGo ads, enthalpy ÄHo ads and entropy ÄSo ads were negative indicating the spontaneous and exothermic adsorption process as well as Olive extract retained the metal ions and reducing the dissolution of steel.