In this paper we present the results of a study of the optical properties of poly (phenylenevinylene), PPV, prepared by the sulphonium polyelectrolyte precursor. We investigate the conditions for the transformation reaction from precursor to PPV using optical and IR absorption. We investigate also the effects of oxidative doping. In situ electrochemical doping shows the appearance of new absorption features at 0.9 and 2.3 eV which correlate with π-π* interband bleaching at 3.0 eV and which may be assigned to valence band to bipolaron level transitions. Chemical doping with iodine and with AsF5 introduces new infrared absorption features at 1151, 1286, 1317, 1420 and 1506 cm-1. © 1987.