Abstract: Ethanol extract of Bagassa guianensis was tested as corrosion inhibitor for zinc in ASTM medium using polarization and electrochemical impedance spectroscopy (EIS). The results obtained show that this plant extract could serve as an effective inhibitor for the corrosion of zinc in sodium chloride media. The extract obtained give inhibition around 85%. Polarization curves show that Bagassa guianensis extract affects the anodic and cathodic reactions and the corrosion potential values were shifted to the positive potentials in the presence of the crude extract in the ASTM medium. The experimental data obtained from EIS method show a frequency distribution and therefore a modelling element with frequency dispersion behavior, a constant phase element (CPE alpha,Q ) has been used. Graphical methods are illustrated by synthetic data to determine the parameter of CPE (alpha, Q). Studies on the phytochemical constituents of thetotal extract were also established. Electrochemical studies, on the chemical families present in the crude extract, were also carried out to find the main constituents responsible for corrosion inhibition properties of the plant extract.