In this study, a ter-polymer film of pyrrole, o-anisidine and o-toluidine has been electrochemically synthesized on low carbon steel. The synthesis solution was aqueous oxalic acid containing 2:1:1 monomer feed ratio between pyrrole, o-anisidine and o-toluidine, respectively. The characterization of synthesized ter-polymer film was realized with help of UV-Vis absorption, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) techniques. The stability of this ter-polymer film as a coating material has also been investigated on steel, in 3.5% NaCl solution. Under such severe conditions, the ter-polymer film was found to exhibit low permeability against water ingress. It was able to exhibit protective coating behavior on steel, even after 72 h exposure time. The DSC results revealed that the ter-polymer film had better thermal stability with respect to single polypyrrole film. The synthesized ter-polymer film was completely different in aspect of morphology, stability and other structural properties when compared to single polypyrrole film. This highly stable and extremely thin (0.80 mu m) film can find application for various purposes (anticorrosive, electrocatalytic, etc.), at where the stability of polypyrrole like films constitutes a drawback. (c) 2009 Elsevier B.V. All rights reserved.