The corrosion inhibition effect of Isatin-Aniline (HIAN) Schiff base for carbon steel in 1M HCl was studied by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and monograph techniques. Weight loss was studied for different immersion time with varying concentrations of inhibitor at 250C. The results obtained from the calculated data showed increasing in inhibition efficiency and surface coverage but decreasing in corrosion rate with increasing inhibitor concentration. HIAN showed maximum inhibition efficiency of 89.7% at 200ppm concentration. This might be due to the adsorption of inhibitor molecule on the surface of metal. Polarization data depicted that with the addition of inhibitor there is reduction in the anodic dissolution and retardation in the cathodic hydrogen evolution of carbon steel which describes it as a mixed type of inhibitor. EIS data revealed the dependence of corrosion process on charge transfer process. Surface morphology was analyzed by metallurgical microscope All these results showed that HIAN as an effective inhibitor for carbon steel with good IE%.