Methanolic extract of Artemisia pallens was tested as corrosion inhibitor for mild steel in 4N HCl and conc. HCl. Weight loss and polarization techniques were used for evaluating corrosion inhibition in 4N HCl, whilst weight loss, SEM and FT-IR studies were carried out in conc. HCl. The inhibition efficiency was found to increase with increase of the inhibitor concentrations due to the adsorption of the inhibitor molecules on the metal surface and the adsorption follows Langmuir's adsorption isotherm. The inhibition efficiency was found to be 93% at 1.5 gl(-1) in 4N HCl and 96.5% at 40 gl(-1) in conc. HCl. (C) 2009 Elsevier B.V. All rights reserved.