Thermochemical energy storage is a promising technology to store heat. The heat is stored as reaction enthalpy and can then be released again via the reverse reaction. With this technology it is possible to store waste heat and therefore increase the efficiency of a plant. Additionally, it is easier to install renewable energy sources since it is possible to counter the fluctuating energy production of these kind of plants. One of these storage systems is the system B2O3/H3BO3. In this thesis the heat production is studied. This follows the reaction B2O3 + 3H2O -- 2H3BO3 + delta HR A preceding work showed, that a high water excess is necessary to ensure homogeneous mixing of water and boron oxide. But since water has a relatively high cp-value, this excess water reduces the maximal reachable temperature. To counter this, some of the water was substituted with a solvent with a lower cp, therefore increasing the maximal temperature. During the experiments, also the reaction between alcohols and boron trioxide was tested for their possibility as thermochemical energy storage. After a broad study of various solvents, a more detailed study with selected solvents followed. Therefore, various starting temperatures as well as various mass relationships between reacting agents and solvent were tested. Additionally, a comparison with the reaction without solvent was done. An additional comparison was done between a suspension in solvent and a suspension in pure water. The observation criterium was the temperature increase during the reaction. This was higher in methyl isobutyl ketone, compared to pure water. The conversion was determined by various analytical methods, as well as with a calculation using the temperature increase over the reaction time.