INTRODUCTION Conducting polymers are polymeric materials that have both metallic and semiconductor characteristics. A key property of a conductive polymer is the presence of conjugated double bonds along the backbone of the polymer. Conducting polymers (CPs) have been attracting attention of material scientists and electrochemists for many years because of their simple preparation, high electroconductivity, as well as good-looking electrochemical and optical properties 1 . Lignin is a polymeric component naturally found in the cell walls of higher order plants. It forms a highly efficient ORIENTAL JOURNAL OF CHEMISTRY www.orientjchem.org An International Open Free Access, Peer Reviewed Research Journal ISSN: 0970-020 X CODEN: OJCHEG 2013, Vol. 29, No. (4): Pg. 1359-1369 Electrochemical Study of Conducting Polymer/Lignin Composites YILKAL DESSIE and SHIMELIS ADMASSIE Department of Chemistry, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia. *Corresponding author E-mail: yilikaldessie@gmail.com http://dx.doi.org/10.13005/ojc/290411 (Received: May 24, 2013; Accepted: July 24, 2013) ABSTRACT Electropolymerization and redox behavior of lignin composites were characterized by cyclic voltammetry (CV), electrochemical quartz crystal microbalance (EQCM), and Fourier transform infrared spectroscopy (FTIR). Oxidation of lignin (LG) composites mixed with different polymers such as; Poly (o-phenylenediamine) (POPDA), Pyrrole (Py), 4-amino-3-hydroxynaphthalene-sulfonic acid (AHNSA) on working glassy carbon electrode (GCE) were performed by cyclic voltammetry in a three-electrode electrochemical cell. EQCM was used during polymerization technique and detecting the continuous mass increase with the number of potential cycles. Transmission FTIR spectra of the electropolymerized film of pyrrole and lignin composite polymer after deposition were recorded. These results gave evidence of lignin composite formation due to the fact that new and broad bands in the region of 3411"3460 cm ”1 were observed. Keywords: Lignin, Poly (o-phenylenediamine), Pyrrole, 4-amino-3-hydroxynaphthalene- sulfonic acid, Composite electrode, Electrosynthesis, Cyclic voltammetry, composite system with cellulose and hemicelluloses (carbohydrate polymers). Lignin’s role in this composite is to act as a matrix material that binds the plant polysaccharide and fibers, there by imparting the strength and rigidity to the plant stem necessary for vertical growth 2 . Lignin molecules are derived mainly from three phenylpropane monomers: p-coumaryl alcohol, coniferyl alcohol, and synapyl alcohol (Fig.1). Monolignols are polymerized by a radical coupling process that links them by carbon-carbon or ether bonds 3-6 . After synthesis of conducting polymers characterization of the material is an important step