Thin film devices made with Poly(2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene), MEH-PPV, are known to be efficient light emitting diodes. The same devices, under reverse bias, exhibit excellent photosensitivity. Large photovoltages were observed in devices with selected metals as the cathode and anode electrodes. The open-circuit voltage, V-oc, varies with the work functions of the electrodes; in most cases, V-oc approaches the work function difference between the two electrodes at high excitation levels. The photosensitivity increases significantly under reverse bias. At -10 V, the sensitivity in Ca/MEH-PPV devices reaches 45 mA/Watt at 20 mW/cm(2) (quantum yield of similar to 13% electrons/photon). The action spectra of the photovoltaic signal at zero bias, and the photocurrent at 2V forward bias follow the absorption spectrum at the band edge. Thus, mobile carriers can be generated either by charge injection at the contacts or by interband photoexcitation, as observed in inorganic semiconductors.