The corrosion behavior of 316L stainless steel in the presence of various Cl^- ions concentrations at constant dose (ZOP) inhibitor has been investigated electrochemically by Tefal Scan, Potentiodynamic, Cyclic polarization and Electrochemical Impedance spectroscopy (EIS). These techniques evaluated that the probability of pitting to occur and effect of ZOP inhibitor on pitting resistance. The corrosion inhibition by (ZOP) was due to formation of passive film which obstructed the approach of aggressive anions at the surface. The effect of ZOP inhibitor was more pronounced at 100ppm Cl^- ions concentration. Increase in Cl^- ion concentration in solution not only shifted the pitting potential towards negative direction but also adversely affected the inhibitor efficiency of ZOP which resulted in high corrosion rate.