The unique pattern of uptake of Cr(bpy)(3)(3+) at clay-modified electrodes can be attributed to two factors as deduced from experiments with Co(bpy)(3)(3+), Co(bpy)(3)(2+), and(-)d-Cr(bpy)(3)(3+). In the first case, transport of the trivalent species is accelerated across the film because of electrostatic considerations. The initial swelling of the clay film controls the extent of accelerated transport through the film by establishing the interlayer dimensions. Valence, however, does not completely control the pattern of loading of the clay film with the complex. Cr(bpy)(3)(3+) and Co(bpy)(3)(3+) exhibit different rates of adsorption by the clay surface which contribute to the differing non-equilibrium loading patterns.