A simple and template-free chemical synthesis of nanowires of poly(thionine) (PTHNWs) by catalytic reaction of thionine in the presence of FeCl3 and hydrogen peroxide is presented. Spectroscopic characterization indicates that the PTHNWs are formed successfully by the oxidation of monomer units through secondary amino-bridging and that contain free amine groups. The chemically synthesized PTHNWs show electrochemical properties comparable to those of a thin film of poly(thionine) (PTH) prepared by electrochemical deposition on a glassy carbon (GC) substrate, which will facilitate their application to various types of electrochemical sensor. (C) 2013 Elsevier B.V. All rights reserved.