Conducting polymers bearing nitro substituents are very important from both academic and industrial viewpoints. However, it is very difficult to electrosynthesize such conducting polymers because of the strong electron-withdrawing effect of nitro groups. In this article, we describe the electrochemical synthesis of films of a new conducting polymer, high-quality poly(6-nitroindole) (P6NI), by direct anodic oxidation of 6-nitroindole in boron trifluoride diethyl etherate containing 10% (v/v) diethyl ether. The oxidation potential onset of 6-nitroindole in this medium has been measured to be just 0.98 V versus a saturated calomel electrode (SCE), which is much lower than that determined in acetonitrile containing 0.1 mol/L tetrabutylammonium tetrafluoroborate (1.6 V vs SCE). Thermal studies have revealed that P6NI displays good thermal stability. The electrical conductivity of the P6NI films has been measured to be 0.08 S/cm. Structural studies have shown that the polymerization of the 6-nitroindole ring occurs mainly at the 2,3-positions. Fluorescence spectral studies have shown that the principal excitation and emission peaks of P6NI are at 416 and 535 nm, respectively, with a fluorescence quantum yield of 0.05. All these properties of P6NI films may facilitate their potential applications in various fields, such as electrochemical sensors and green-light-emitting materials. To the best of our knowledge, this is the first report on the electrosynthesis and characterization of 6-nitro-substituted polyindole films. (c) 2007 Wiley Periodicals, Inc.