Electrochcmical and ex situ FTIR spectral techniques have been used to study the insertion of asymmetric alkyl viologen, N-ethyl-N'-octadecyl viologen (C18EV2+) into the self-assembled monolayers (SAMs) of octadecanethiol (ODT) on Au electrode surface. in the IR reflection absorption (IRRA) spectroscopic measurements, the relative magnitude of the -CH2- and CH3-stretching modes of ODT and their peak positions indicated that ODT forms a densely packed crystalline-like assembly on polycrystalline Au electrode. Furthermore, a considerable increase in the -CH2- stretching mode intensity relative to that of the CH3- stretching mode in the C18EV2+-insertcd ODT monolayer suggested a greater disorder in the alkyl chains of the C18EV2+-intercalated ODT monolayer than in the pure ODT monolayer. In the cyclic voltammetry studies, C18EV2+ showed a neat broad redox wave at low surface coverage of C18EV2+ on the ODT-coated electrode and a sharp reduction and multiple oxidation peaks at high surface coverage, The potential difference subtractively normalized interfacial FTIR (SNIFTlR) spectral studies showed that at high surface coverage of C18EV2+ inserted on the ODT-coated electrode, the electrogenerated radical cations of C18EV2+ are close and in an ol icntation proper enough to form the dimer; the spectral features characteristic of the dimer were observed. On the other hand, at similar surface coverage of C18EV2+, such spectral features were not observed for the SAMs of C18EV2+ on bare Au electrode because of the less ordered orientation of C18EV2+.