Thermochemical energy storage (TCES) is a promising new technology to increase efficiency and support sustainable energy generation with distinct advantages compared to other thermal energy storage systems. In this thesis, the magnesium oxide/magnesium hydroxide system is experimentally investigated in a fluidized bed reactor (FBR) for its applicability as a TCES material pair. Basic fluid dynamic quantities, mechanical stability, hydration and dehydration kinetics as well as reversibility under repetitive reaction conditions are determined. For testing, two different types of material are considered (carbonate-bases/hydroxide-based). Overall, materials show good fluidization behavior. Mechanical stability is given for all investigated conditions, except for hydroxide-based material under stress of dehydration. The influence of reaction parameters on hydration/dehydration kinetics is clearly shown. At 0.4 bar partial steam pressure and 80 C as well as 0.6 bar and 100 C, 60% to 80% conversion is reached after 3 h with a maximum conversion rate of about 2 104 s1. At 0.4 bar and 100 C conversion stays below 20 %. Carbonate-based material exhibits an acceleration of kinetics after the initial cycle up to a maximum of 5 104 s1. Dehydration, with a fivefold increase in specific surface area (SSA) compared to initial material, is found to be the reason. Hydroxide-based material is accompanied by a surface area increase up to tenfold, but it shows fast deterioration for consecutive cycles. Carbonate-based material is more stable under repetitive reaction conditions. Compared to lab-scale simultaneous thermal analysis (STA) experiments, kinetic improvement is achieved. From second cycle hydration on, a maximum discharge power of about 1 kW/kg is possible. Discharge capacity is, however, limited to 50% of maximum value, even if a lower discharge power is accepted. The investigated reaction system shows sufficient properties for application as a possible low temperature storage material. Especially if materials are further optimized, also in regard to utilization in a FBR, their applicability as TCES system could be enhanced.