The effect of cytochrome-C, hemoglobin, and myoglobin on photo-osmosis through liquid membrane bilayers generated by bacteriorhodopsin (BR) has been studied. The magnitude of photo-osmotic velocity was found to be much greater when BR was combined with any one of the three pigments than that of BR alone. This has been because of the exclusion of protons and electrons in the illuminated compartment by the action of light, where one acts as the acceptor for the others. The rate of light-induced volume flux of the combined system depends on temperature, intensity, and wavelength of incident light, and the nature and concentration of electron donors and accepters.