We investigate whether a high-contrast electronic paper can be formed using a microgel dispersion in which the particles reversibly swell and collapse on cycling the pH. An aqueous dispersion of particles of poly(2-vinylpyridine) crosslinked with divinylbenzene is studied. It is demonstrated that the pH of the dispersion, and hence the state of the microgel particles, can be potentiostatically controlled using a polyaniline electrode. Electrochemical switching of the dispersion from highly scattering to transparent for all visible wavelengths is achieved. Modification of cell and electrode design is required to reduce the switching time, presently greater than 10 min. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012