The development of advanced materials with high energy density for thermochemical energy storage (TCES) may contribute to the utilization of waste heat from industries. Here, magnesium hydroxide doped with lithium nitrate is investigated as a candidate material for TCES. The doping with LiNO3 depresses the dehydration start temperature by 76°C while the dehydration heat is reduced only slightly. Kinetics of the dehydration of the doped material are studied for various salt contents and temperatures. The effect of the salt on dehydration is investigated using a series of complementary physicochemical methods (powder X-ray diffraction, infrared spectroscopy, N2 adsorption) and a thermodynamic model of the effect is discussed.