Hexa propylene glycol cyclotriphosphazene(HPGCP)was used as corrosion inhibitor and its inhibiting action on the corrosion of carbon steel in 3% NaCl solution was investigated using weight loss test potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques method has been employed in this study. Results indicated that the HPGCP compound acted as an anodic inhibitor. The inhibition efficiency of carbon steel increased with increasing concentrations of the inhibitor.