ZnSO4　center　dot　7H(2)O　is　a　promising　thermochemical　heat　storage　material.　In　this　paper,　we　report　a　detailed　thermodynamic　study　of　ZnSO4　center　dot　7H(2)O　based　on　hydration/dehydration,　cyclicability,　and　water　sorption　performance.　The　TG-DSC　measurements　reported　that　at　below　120　degrees　C,　1747　and　1298　J　g(-1)enthalpy　was　recorded　for　dehydration　and　hydration,　respectively.　The　relative-humidity　study　showed　that　at　75%　RH　(0.148　g/g),　the　water　sorption　can　be　significantly　improved　compared　to　lower　humidity　(65%　0.131).　The　XRD　study　highlighted　that　the　main　structure　of　ZnSO4　after　thermal　treatment　remains　unchanged.