A copolymer based on thiophene and anthracene was prepared on indium tin oxide (ITO) glass electrode via electrochemical copolymerization in boron trifluoride diethyl etherate (BFEE). The resultant copolymer is characterized by cyclic voltammetry, FT-IR, XPS, SEM and spectroelectrochemical analysis. The copolymer film presents multicolor electrochromism and can exhibit six colors (yellowish red, yellow, yellow green, blue green, light blue and dark blue) under various applied potentials. The optical contrasts of the copolymer film at 491.767 and 1100 nm are 21%, 38% and 37%, respectively, and the corresponding switching rates are 1.9, 1.3 and 2.3 s. The film has superior coloration efficiency which is calculated to be 327 cm(2) C-1 (491 nm), 240 cm(2) C-1 (767 nm) and 296 cm(2) C-1 (1100 nm). Furthermore, the film presents reasonable electrochemical and optical stability which retains 73% of its original electroactivity after 500 cycles and 73.6% of its optical contrast after 800 steps. All of these indicate the satisfactory electrochromic properties of the copolymer film. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.