Self-doped poly(indole-5-carboxylic acid) (P5CO(2)H) is electrodeposited from acetonitrile containing 0.1M LiClO4 as electrolyte and characterized by UV-vis, IR, cyclic voltammetry, and scanning electron microscopy techniques. The polymer is evaluated as a cathode active material together with a Zn anode in rechargeable cells containing 1M ZnSO4 at pH 5. The cell shows an open circuit voltage of 1.36 V and a specific capacity of 67 Ah kg(-1). The ac impedance study shows a predominant diffusion mechanism. (c) 2005 Wiley Periodicals, Inc.