Progress in recent years in the field of electrochromic displays based on viologen modified high-surface area TiO2 electrodes (Vio(2+)/TiO2) has moved the technology towards commercialisation. Viologen molecules (Vio(2+)), derivatised with phosphonic acid attachment groups can be chemisorbed on nanostructured TiO2 layers of thickness 2-10 mu m. Characterisation by cyclic voltammetry, spectroelectrochemistry and impedance spectroscopy demonstrates that colourless Vio(2+)/TiO2 is reversibly reduced to the strongly coloured cation radical species Vio(+center dot)/TiO2. This system can constitute the working electrode of an electrochromic display with a capacitive doped SnO2 electrode as counter electrode, the latter coated by an electrochemically inert white fight-reflecting layer. Such a device is stable upon repeated colouration-bleaching cycles with a bleached-to-coloured state contrast ratio exceeding 5. Multicolour displays can be achieved by patterning different electrochromophores onto different areas of one working electrode. (C) 2007 Elsevier Ltd. All rights reserved.