A range of structurally different cage complexes are shown to be incorporated in high concentrations in thin (ca.0.5-5 mu m) Nafion(R) films covering graphite electrodes. The incorporated cage complexes show well-defined cyclic and square-wave voltammograms with reduction potential shifts which reflect the biphasic hydrophilic and hydrophobic composition of Nafion(R). The large partition ratios relative to aqueous electrolyte solution also have interesting analytical perspectives. Finite film-thickness effects are reflected in deviations from linear Randles-Sevcik plots at small scan rates. The concentration dependence of the apparent diffusion coefficients obtained from the linear part of the Randles-Sevik plots points to mobility of the cage complexes rather than electron hopping as the dominating charge transport mechanism. Both diffusion and migration appear important. Nafion(R) + cage compound electrodes in contact with buffer solutions containing cytochrome c or plastocyanin have so far not shown voltammetric signal changes compared with the signal from the Nafion(R) + cage compound electrodes in protein-free buffer. However, the question of cage compound-protein electron exchange is unresolved at present. Glucose oxidase is denatured at the interface with subsequent transport and adsorption of the flavin group in the Nafion(R) film region.