Thermal storage is akey technology for the transitionto a 100 % renewable energy society.Nowadaysusedphysical heat storage systems showdisadvantages like high demand for space and heat loss over time.Thermochemical heat storage systems offerthe potential to store ten times more heat per volume than physical heat storageunits, and this without heat loss over time. Thermochemical systems are based on reversible chemical reactions,mainlygas-solid reactions. The easy separation of the gaseousand solid compound allows a good control of the storage system.Our project is focused on the investigation of thermochemical materials (TCM) in order to develop a high efficient thermal battery for building and industrial applications. Of particularinterest are TCM such as salt hydrates and metal hydroxides, which tend to agglomerateor expand.Thus,the cycle ability and mass transfer are compromised. In addition, salt hydrates show low thermalconductivity and therefore present severe limitations for the heat transfer. Heat transfer in wet porous media is strongly influenced by the effects evaporation-condensation induced by the diffusive transfer of the vapor within the medium.By impregnatingsalt hydrates onto porous carrier matricesand novel synthesis of complex salts, we expect to improvethose properties. At micro scale,characterizationis performed using simultaneous thermogravimetric analysis and differential scan calorimetry(TGA/DSC.Macro scale experiments are conductedina lab scale reactor for comparison and improvement.