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 (PF - 6 ) 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 PF - 6 ions, resulting in dimerization.