The inhibiting properties of two synthesized metals (alkyl)-2-hydroxy benzene sulfonate compounds have been studied on the corrosion of steel (St-3) in aerated 0.1N H2SO4 solutions by potentiodynamic polarization (dc) technique and electrochemical impedance spectroscopy (ac). The polarization curves indicate that the inhibitors are mixed-type. The impedance increases with inhibitors concentration. Low difference in inhibition efficiencies of two compounds for the corrosion of St-3 steel could be explained by high similarities of their structures. Results obtained by both electrochemical methods are in relatively good agreement. (c) 2007 Elsevier Ltd. All rights reserved.