Electrochemical polymerization of the aniline, o-anisidine and o-toluidine coatings on low carbon steel has been carried out under galvanostatic conditions in an aqueous oxalic acid solution. The E-t curves show three distinct stages - dissolution of the low carbon steel surface and formation of polycrystalline iron oxalate interphase, complete passivation of low carbon steel surface and the electrochemical polymerization of respective monomer(s). To understand the role of monomer(s) during the electrochemical polymerization process, the passive interphase samples were characterized by X-ray photoelectron spectroscopy. The results of this study show that monomer(s) are taking a part in first stage of electrochemical polymerization and passivation time depends on the type of monomer(s) present in electrolyte. (C) 2012 Elsevier Ltd. All rights reserved.