The inhibition effect and adsorption behavior of a novel dissymmetric bisquaternary ammonium salt (DBA) for Q235 steel in 1 mol•L^－1 HCl solution were investigated using weight loss measurements, polarization curve and electrochemical impedance spectroscopy (EIS) methods. The results showed that inhibition efficiency increased with the increase of concentration, and its inhibition efficiency was above 90% at a concentration of 2.89×10^－4 mol•L^－1. The inhibition efficiency increased gradually in the temperature range of 25～55 ℃. Polarization curve results revealed that DBA was a mix-type inhibitor which mainly inhibited cathodic process. The adsorption processes were endothermic and belonged to the chemical adsorption, obeying the Langmuir isotherm. The relationship between the molecular structure of DBA and the inhibition efficiency was investigated using quantum chemical calculations.

Key words: corrosion inhibitor, dissymmetric bisquaternary ammonium salt, corrosion inhibition, adsorption, quantum chemistry