A number of properties of polypyrrole were examined using the current response to a photoflash on a millisecond time scale. Cathodic photoeffects were seen from - 0.4 to 1.1 V (standard hydrogen electrode (she)) in aqueous 0.5 M HCI, and were more prolonged for polypyrrole in an oxidised and conducting state(> 0 V). The photocurrents in the reduced state lasted only as long as the light from the flash unit and were ascribed to reactions at the solution | excited polymer interface producing a capacitive charge across the film. In the conducting state, local temperature changes following the photoflash produced a shift in the state of redox charge, favouring the endothermic process and release of counter-ions. Overoxidation of polypyrrole led to a decrease in the intensity of the photocurrents, and the progressive reduction of an oxidised film was monitored as a decline in the photocurrent on a logarithmic time scale. The photocurrent profile for bilayers of polypyrrole and polyaniline were dominated by polypyrrole, with unique features also displayed.