Thermal energy storage by chemical reactions is one of the most suitable energy storage systems for buildings and industrial applications due to the wide range of working temperatures as well as the high energy storage density provided. Developing and characterizing chemical reactions is now one of the most promising areas of research. Chemical heat pumps are one of the systems used when chemical reactions are utilized as thermochemical energy storage technology. Nevertheless, the main problem to implement this technology is found in the material behaviour within the reactors used. Therefore, material and reaction characterization have been identified as key issues to design a proper system. The main goal of this paper is to highlight the parameters to take into account previous to the design.