Abstract: In a chemical heat pump involving a sorption process and a matrix holding an active substance, at least the active substance is in a material comprising graphene and/or graphene oxide. This material is designed to take use of the great energy content in some salts and making the whole range from diluted solutions to solid crystals available. The heat transfer to and from the active substance is improved, the ability of the matrix to hold active substance in liquid state is improved, the mechanical strength of the matrix is improved, power and energy can be varied better according to requirements in a specific application, the system pressure becomes more flexible.