Electrochemical measurements of hydrogen permeation through Pd/Nb multilayers on Pd substrates are described. Pronounced retardation of permeation is observed for small hydrogen contents. To clarify whether this effect is due to special interface hydrogen states; the permeation is modeled based on the bulk properties of the pure metals. The model is sufficient to explain the retardation; which stems from the different free energies of hydrogen dissolution in both metals. At higher hydrogen contents a more complicated permeation behavior is observed; which is not yet well understood.