A new electrochoromic polymer poly(8,11-bis(3,4-ethylenedioxy thiophen-2-yl)acenaphtho[1,2-b]-quinoxaline) (PBEAQ) was synthesized by electrochemical polymerization of the corresponding monomer (BEAQ) in a 0.1 M tetraethylammonium tetrafluoroborate (TEABF(4)) dichloromethane acetonitrile (2 : 1, v : v) solution. The monomer and polymer were characterized by elemental analysis, H-1-NMR, IR, and UV-vis spectroscopy. The electrochemical and optical properties of polymer were investigated by cyclic voltammetry and UV-vis spectroscopy. Cyclic voltammetry and spectroelectrochemistry studies demonstrated that the polymer can be reversibly reduced and oxidized (both n- and p-doped) between -2 V and +1.5 V vs. Ag/Ag+. The polymer had a transmissive light blue color in the oxidized state and reddish color in the reduced state. Undoped polymer shows UV-vis absorption peaks at 615 nm in solution, 650 nm in solid state, and has an optical band gap of 1.5 eV. (c) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 74-80, 2010