Thermochemical energy storage (TCES) is an emerging technology promising for reuse of industrial waste heat and harvesting solar energy. Recently, a novel material, namely, a magnesium hydroxide doped with lithium nitrate LiNO 3 /Mg(OH) 2 , was suggested for TCES at temperature lower than 300 °C . The LiNO 3 additive to Mg(OH) 2 was found to decrease the Mg(OH) 2 dehydration temperature by 76 °C which, to the best of our knowledge, is the largest depression reported in the literature so far. The large heat storage capacity (1250 J/g) and fast dehydration made this material promising for TCES. In this work, the LiNO 3 /Mg(OH) 2 is studied with a focus on the reverse reaction of its hydration by water vapour which allows the stored heat to be released. The rehydration kinetics is studied at various temperatures (90–150 °C), water vapour pressures (16.7–33.5 kPa), and LiNO 3 contents (0.5–20 wt.%) to outline the boundary conditions of closed TCES cycle for which this material may be used. The material is found to be stable in ten successive de-/rehydration cycles. Finally, the applicability of the material for storage of heat from some particular heat sources is discussed.