The binary inhibitor system L-aspartic acid - Zn²⁺ has been investigated by weight loss method. A synergistic effect exists between L-aspartic acid and Zn²⁺ system. The formulation consisting of L-aspartic acid - Zn²⁺ offers 90% inhibition efficiency (IE). Polarization study reveals that this formulation functions as an anodic inhibitor. AC impedance spectra reveal that a protective film is formed on the metal surface. At isoelectric point, the IEs of L-aspartic acid and also the L-aspartic acid -Zn²⁺ systems are very low. In some cases there is acceleration of corrosion negative IEs (-25%).