The temperature dependent optical properties of certain thin films are used in so-called thermochromic devices. As an alternative to a single layer of, e.g. VO₂, which displays a temperature dependent optical transmission, we propose the use of an encapsulated metal-hydride bilayer (i.e. a switchable mirror and a hydrogen storage layer). Due to differences in the thermodynamic properties of the two metal-hydride layers, a temperature change results in the migration of hydrogen from one layer to the other, thereby changing the optical properties of the switchable mirror metal-hydride. Depending on the materials chosen the transition can be optimized for transmission, reflection or absorption. Hence, the use of metal-hydride bilayers allows the fabrication of a thermochromic absorber. The thermodynamical background and the first results of such an all-solid-state thermochromic device are presented.