Within the past decade, ecological issues accompanying energy generation and utilization have gained increasing interest, thereby creating a need for new scientific and technical solutions on the path to a sustainable energy future. Besides switching the basis of the electricity sector from fossil fuels to renewables, also the heat sector is to be transformed. A major obstacle accompanying this energy transition is the temporal intermittency of power generation from renewables. However, these hurdles can be overcome by design of systems for energy storage and conversion. Within the growing field of solutions for thermal storage, thermochemical systems move into the focus as they provide comparably highest storage densities but at the same time also options for heat conversion. This concise review summarizes the background and the scope of possible applications discussed in recent literature. A focus is set on the identification and modification of new reaction systems, criteria for material selection are presented and different classes of reaction systems are discussed with regard to their operating temperature ranges. It is concluded, that an evaluation of possible use cases with precise definition of their respective thermal boundary conditions would be of high value for a purposeful continuation of future screening approaches.