Rectification was observed across a monolayer of 2,6-di [dibutylamino-phenylvinyl]- 1-butylpyridinium iodide, (Bu(2)NphiV)(2)BuPy+I-, 1 sandwiched between gold electrodes. The current is enhanced at a forward bias above 0.5 to 1.0 V, as electrons flow preferentially from the iodide ions to the pyridinium ring, and is as high as 100 000 electrons molecule(-1) s(-1), with a rectification ratio of up to 90.