Porphyrin derivatives have been synthesized and embedded in bilayer lipid membranes, in order to promote a transmembrane photoconduction in the presence of aqueous phase redox compounds. The molecules have to be accessible for interfacial redox electron transfers, either by moving, or by spanning the membrane. The transmembrane charge transfer is effected by the movement of the charge oxidized form of simple mobile porphyrins through the membrane. Contrarily, in the case of the carotenoporphyrinquinone triad and of the face to face triporphyrins, the intramembrane electron transfer is an intramolecular one. On the basis of the proposed mechanism, the experimental variation of the photocurrents with various physicochemical parameters can be accounted for. Both stationary and transient photocurrents have been measured and simulated. The multicenter molecules are good models of photosynthetic reaction centers; moreover, they function as organic phototransistor devices.