The molecular rectifier consisting of protein heterolayer is investigated in molecular-scale for the construction of bioelectronic device. Cytochrome c and green fluorescence protein were used as an electron acceptor and a sensitizer in the molecular layer by mimicking the bacterial photosynthesis. Self-assembled monolayer of thiol-modified cytochrome c was formed on Au coated glass, and then green fluorescence protein was adsorbed onto the cytochrome c surface by electrostatic attraction. The formation of cytochrome c layer onto the An substrate and green fluorescence protein adsorption onto the cytochrome c layer were observed by the surface plasmon resonance measurement. The surface of heterolayer was observed and analyzed by the scanning tunneling microscopy. The rectifying property of proposed heterolayer was achieved by the scanning tunneling spectroscopy based current-voltage measurement. Finally, the molecular rectifying property was verified. (c) 2005 Elsevier B.V. All rights reserved.