The corrosion inhibition of Al and its alloys are the subject of tremendous technological importance due to the increased industrial applications of these materials. This paper reports the results of weight loss, potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) measurements on the corrosion inhibition of Al, (Al + 6%Cu) and (Al + 6%Si) alloys in 1.0 M HCl in the temperature range 10-60degreesC using dodecyl benzene sulphonate as an anionic surfactant (AS) inhibitor. The results showed that the addition of the surfactant inhibits the hydrochloric acid corrosion of the three Al samples. The inhibition occurs through adsorption of the surfactant on the metal surface without modifying the mechanism of corrosion process. The surfactant acts predominately as cathodic inhibitor. The inhibition efficiency increases with an increase in the surfactant concentration, but decreases with an increase in temperature. Maximum inhibition is observed around its critical micelle concentration (CMC). The inhibition efficiency for the three Al samples decreases in the order: (Al + 6%Si) > (Al + 6%Cu) > Al. Frumkin adsorption isotherm fits well with the experimental data. Thermodynamic functions for both dissolution and adsorption processes were determined. Results obtained from the three methods are in good agreement. (C) 2002 Elsevier Science B.V All rights reserved.