N-octadecylviologen-TCNQ(2)(-) salt (OV-(TCNQ)(2)) was synthesized and identified by its characteristic NMR peaks. Charge transfer absorption of the TCNQ anion radical was observed at 600 similar to 900 nm and the intramolecular transition of TCNQ anion radical was observed at 400 nm in a methylene chloride-acetonitrile (1:1) mixture. A significant shift in electronic transition was observed for a Langmuir-Blodgett film layered with OV-(TCNQ)(2); 600 nm for the dimer and 380 nm for TCNQ anion absorption. The take-off area of OV-(TCNQ)(2) was 180 Angstrom(2) molecule(-1) and the limiting area was 145 Angstrom(2) molecule(-1) at the surface pressure of 25 mN m(-1). Spectroscopic ellipsometry shows that the one-layer thickness of OV-(TCNQ)(2) on a Si wafer is 35 Angstrom. The thickness indicates that both aromatic rings of octadecylviologen are attached on the solid surface. The electrical conductivity of five-layer OV-(TCNQ)(2) was 1.02 x 10(-8) S cm(-1).