The interaction of hydrogen with metallic layer structures and the change of properties of these structures upon hydrogen charging are reviewed. Drastic deviations from the bulk behaviour are observed. The deviations can be traced back to the elastic boundary conditions and to the electron transfer at the interfaces between the different materials. Examples of improvements of the structure or the electronic properties of the layers by hydrogen incorporation are reported. Presently, several groups are trying to change the magnetic coupling of magnetic layers by introducing hydrogen in the non-magnetic spacer layer.