The formulation consisting of 100 ppm Thiourea, 25 ppm Zn2+ and 250 ppm of L-Phenylalanine has 95% corrosion inhibition efficiency with a synergistic effect among Thiourea, L-Phenylalanine and Zn2+ ions. Polarization study shows that this formulation as a mixed inhibitor. FTIR spectra exposed the presence of Fe2+-Thiourea, Fe2+-L-Phenylalanine complex and Zn(OH)2 in protective film. AFM study confirmed the metal surface smoothness following engrossed in the inhibitor and the presence of formed protective film on the metal surface.