Today, synthetic sorption materials are used in thermochemical energy storage systems. The benefit of such systems is that thermal energy can be stored over a long time without any heat loss. The disadvantage of a synthetic zeolite is the high desorption temperature that is required when loading the material and its high costs. Therefore, a new material consisting of a natural zeolite with an extra salt layer was developed. Due to the impregnation the energy density of the natural material could be increased. The main problem of this material is the poor cycle stability. To improve the cycle stability a hydrophobic layer has been added. Due to this layer water cannot reach the surface of the salt and the Clinoptilolite but the extra layer is permeable for vapour. The main focus of this work lies on the material-specific and thermochemical investigation of a newly developed composite material. This material is made of a natural Zeolite (Clinoptilolite), calcium chloride and silane. The material-specific investigations showed the natural origin of Clinoptilolite, the ion exchanging behavior of the zeolite by exchanging the cations of the material (Na, K, Mg and Ba) for the cation of the CaCl2-impregnation (Ca) and the influence of the water-repellent properties of the zeolite. The investigations also showed that the ion exchanging properties of the zeolite are completely brought to a halt. Moreover, the salt is not distributed over the whole surface of the non-hydrophobic material but occurs in individual patches. In contrast, on the surface of the hydrophobic material salt can be detected as single salt crystals, which are distributed equally over the whole surface. In general, the quality of the water repellency is depending on the amount of the salt load and the grain size. In addition to the material-specific investigations the thermochemical description of the composite material has been done. The result of this study showed that the energy density has been increased compared to the carrier material (Clinoptilolite). Furthermore, the temperature lift of the composite material decreased with an increasing salt loading. The SAXS-analysis showed that the decrease is caused by the reduction of the active surface area due to the water repellency treatment by 35%.