For the purpose of a long-term heat storage system based on water sorption, a composite material consisting of CaCl2 and zeolite Ca-X, obtained by ion exchange with Ca2+ and subsequent impregnation with CaCl2 of a binder-free granulated zeolite Na-X, was prepared on a technical scale. In a lab-scale apparatus, the heat storage density of the composite material reaches values up to 260 kWh m(-3) for water vapor partial pressures up to 33 mbar. As compared to the pure zeolites Ca-X and Na-X, this corresponds to an increase in heat storage density of 45% and 68 %, respectively. An engineering concept based on the mechanical transport of the composite heat storage material through a prereactor and a main reactor was demonstrated in a hardware-in-the-loop test bench.