The corrosion behaviour of cationic surfactants, namely: cetyl trimethyl ammonium bromide (CTAB) and dodecyl trimethyl ammonium bromide (DTAB), have been used as corrosion inhibitors for carbon steel in well water. Protection efficiencies of the studied surfactants were depended on the hydrophobic chain length and concentration of the surfactants. The results shows that the order of protection efficiency is CTAB > DTAB. Tafel curves showed these surfactants are acting as an anodic inhibitors. Nyquist curves revealed that a protective film is formed on the metal surface. FTIR spectra suggest that the tested surfactants protective film consists of Fe2+-CTAB, Fe2+-DTAB and Zn(OH)2. Protection efficiency values and synergism parameters obtained weight loss; potentiodynamic polarization and electrochemical impedance spectroscopy are consistent.