Copolymers based on 3,4-ethylenedioxythiophene (EDOT) and naphthalene have been successfully prepared via electropolymerization in boron trifluoride diethyl etherate. Cyclic voltammograms, FTIR, and XPS confirm the formation of copolymers. The EDOT/naphthalene ratio in the polymer chain increases with applied increasing EDOT/naphthalene feed ratio. The copolymers exhibit multicolor electrochromism, and the color can be tuned by controlling the applied feed ratio. The copolymer prepared with EDOT/naphthalene at 8/1 displays multiple colors under various potentials, which presents absorption peak at 531 nm and 1.7 eV in the neutral state. The bleaching and coloration times at 531 nm are 1.2 and 3.6 s, respectively. Furthermore, the copolymer has good optical and electrochemical stability, which only loses 2% of its contrast after 500 steps, and 14% of its electroactivity after 1000 cycles. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.