A thin multilayer dim, formed by alternate deposition of poly(dimethyldiallylammonium chloride) (PDAC) and bacteriorhodopsin (bR) (pH=9), generated a photovoltage with defined polarities upon one flash excitation. Three time constants of 2.59 mu s, 13.64 mu s and 58.03 mu s fitting to the kinetics of photo-voltage were assigned to the decay of K, L-1 and L-2 intermediates of bR photocycle respectively. The positive photovoltage accompanying the formation of M indicated that the cytoplasmic side of PM fragments was directed toward the substrate.