All-solid-state photoelectrochemical cells have been constructed using films of a conducting polymer, poly(3-octylthiophene), and a polymer electrolyte, amorphous polyethylene oxide, complexed with the I-3(-)/I- redox couple. An open-circuit voltage of 250 mV and a short-circuit current of 0.04 mu A/cm(2) were obtained with white light illumination at approximately one sun. During illumination, a cathodic photocurrent was observed, indicating that the neutral poly(3-octylthiophene) behaves as a p-type semiconductor. From the spectral response, the junction responsible for the photocurrent generation is between the conducting polymer and the solid polymer electrolyte. The open-circuit voltage and short-circuit current dependence on intensity and variation of open-circuit voltage with redox couple concentration have also been studied.