This paper presents a high-stability, single-phase hybrid polyelectrolyte (SPHP) applied in a large EC device (5 x 10 cm(2)) using WO3 (electrochromic) and CeO2-TiO2 (counter-electrode-ion storage) electrodes, both produced by Leibniz-Institut of New Materials (Leibniz-INM, Germany). The electrochromic device exhibited excellent color and bleach reversibility, high coloration efficiency (> 35 cm(2)/C) from the first cycle up to more than 60,000 CA cycles, and a maximum constant rate of deintercalation/intercalation (O-out/Q(in) = 1). Its remarkable behavior and high stability render this material an excellent candidate for application in electrochromic devices. (c) 2007 Elsevier B.V. All rights reserved.