Monolayers and multilayers of asymmetric N-ethyl-N＇-tetradecyl (or hexadecyl, octadecyl) viologens adsorbed on a glassy carbon electrode exhibit two couples of well-resolved redox waves for the first reduction in the presence of hexafluorophosphate (PF6-) ion. The redox wave observed at less negative potentials was assigned to the viologen dimer on the electrode surface. These asymmetric viologens were closely packed and well-organized on the electrode surface in the presence of PF6- ions, resulting in dimerization.