Synthetization and evaluation of new chitosan derivatives to work as corrosion inhibitors for mild steel in acidic medium. The synthetization process was checked by Fourier-transformed infrared (FTIR) and the inhibition parameters were screened out by electrochemical measurements as well as surface change according to corrosion or forming a protective film was detected via scanning electron microscope (SEM) and X-ray dispersion. The inhibition efficiency increases with increasing the concentration of the inhibitor and with lowering temperature The inhibition efficiency reached about 96.5% and showed enhancement comparable to chitosan only which reflected to the corrosion rate decreasing. The inhibition was interpreted due to the adsorption of chitosan derivatives on the surface of mild steel. The correlation between concentration of new chitosan derivatives and the inhibition effect was investigated by Potentiodynamic polarization. the adsorption nature of the inhibitor on the metal surface also checked according to Langmuir isotherm.