This paper reports the preparation of conducting films combining linear poly(3,4-ethylenedioxythiophene) (PEDOT) and cross-linked polyethylene oxide (PEO) into semi-interpenetrating networks. Due to the synthetic pathway, PEDOT is distributed within the PEO matrix and specifically along the two outer faces of the film. Such a distribution of the conducting polymer inside the matrix leads to the design of a self-supported and symmetrical PEDOT-Polymer electrolyte-PEDOT electrochromic device which can substitute the usual multilayer configuration. Optical contrast Delta T-630nm (%) up to 33% is reached without contrast loss after 1500 switches. The switching time is 30 s for bleaching with a good memory effect (less than I % decrease of transmittance after I h) of the device. (c) 2008 Elsevier Ltd. All rights reserved.