The adsorption behavior of symmetric N,N’-dialkyl-4,4’-bipyridines (viologens, C(n)V, n = 1-8) on a mercury electrode surface in the presence of alpha- or beta-cyclodextrin (alpha-CD or beta-CD) in aqueous media was investigated by cyclic voltammetry. Both alpha- and beta-CDs associate with viologen molecules in the bulk of the solution to form an inclusion complex, whereas only alpha-CD affects strongly the voltammetric characteristics of surface-adsorbed species. The reduction wave of adsorbed viologens with an alkyl chain length longer than C4V shifted to potentials more negative than that in the absence of alpha-CD, which is consistent with the fact that the alkyl chain portion of viologen molecules is included in the cavity of alpha-CD. It has been shown that the adsorbed complex of viologen dication and alpha-CD, once reduced to the cation radical state, released the CD molecule into the solution and formed a compact layer, as observed in the absence of alpha-CD.