We studied the photoelectrochemical response of polyaniline dispersed in a microporous membrane structure. Films of the composite were obtained by electropolymerization of aniline on a platinum electrode coated with a microporous cellulose acetate membrane. They were characterized by UV-Visible spectroscopy, scanning electron microscopy and electrochemical impedance spectroscopy. We compared the results with a electrochemically synthesized polyaniline and a composite film prepared by casting. The photocurrent response of polyaniline is enhanced by its dispersion in the pores,of the membrane. Depending on the potential applied to the electrode, we observe in both cases an n- or p-type semiconductor photoresponse. (C) 1998 Elsevier Science S.A. All rights reserved.9614954