1,4/1,6-Bis(alpha-octylpyridiniuin)butane/hexane dibromide have been synthesized. The inhibitive effect of the two Gemini surfactants for A3 steel in 20% hydrochloric acid solution medium was investigated by mass loss, Tafel extrapolation method and electrochemical impedance spectroscopy. The result of mass loss indicated that the inhibitive efficiency of the surfactants increases with the rise of concentration; decreases with the rise of temperature and is up to the highest at a concentration of surfactants much less than their critical micelle concentration. Polarization data indicates that these compounds act as very good inhibitors of iron in 20% HCl both for cathode and anode. Electrochemical impedance spectroscopy has the same trend of inhibitive effect as that of the polarization data, which indicate the formation of a protective layer on the iron surface by the adsorption of surfactants molecules. (c) 2007 Elsevier B.V. All rights reserved.