We herein report the electrosynthesis of the all-sulfur analog of PEDOT, poly(3,4-ethylenedithiathiophene) (PEDTT), in air and moisture stable ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF(6)). The as-obtained PEDTT film was studied by FT-IR, SEM, GPC, UV-vis spectroscopy, fluorescence and thermal analysis, respectively. Electrochemistry results demonstrated that PEDTT film could be further doped by cyclic voltammetry to substantially improve its doping level. Besides, PEDTT exhibits electrochromic nature with its color changing from golden brown in its reduced form to grass green upon oxidation. By further investigation, PEDTT was also found to reveal favorable coloration efficiency of 127 cm(2) C-1 comparable to PEDOT, low switching voltages and favorable electroactivity and stability. (c) 2013 Elsevier Ltd. All rights reserved.