The anti-corrosive activity of chitosan (CT) on mild steel in HCl solutions was determined using gravimetric and electrochemical methods such linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods. The gravimetric measurements indicated that the inhibition efficiencies of CT 47.62 - 64.25%. The LPR results gave the experimental inhibition efficiency of CT to be 67.46-97.85 % while potentiodynamic polarization resistant method was 56.19 - 89.09%. The EIS measurements indicated 78.45 - 90.96 % as an inhibition efficiencies of CT.