The phase stability of the rarely studied diisopropylammonium chloride hemihydrate (DPC-HH) was investigated in a range of temperature from 100 K to 503 K. The single crystals of DPC-HH grown from methanol solution belong to orthorhombic crystal system with space group Ccca at ambient conditions (296 K) and do not show any phase transformation till 100 K upon cooling whereas it is physically less stable when stored at room temperature due to host-guest nature of the diisopropylammonium chloride (DPC) and water in the DPC-HH lattices. While heating above room temperature dehydration of the hydrate molecules occurs which leads to the crystallization of anhydrous DPC in monoclinic crystal system with space group P21 at 342 K and further at 439.7 K the DPC undergoes a ferroelectric to paraelectric phase transition through a structural transformation from monoclinic P21 to P21/m which is reversible. The Hirshfeld surface and fingerprint plots were used to study the intermolecular interactions of DPC-HH. The intermolecular H⋯H contacts was most significant interactions present in the crystal with over 72% of the total Hirshfeld surface. Powder X-ray diffraction, Raman and FT-IR spectroscopy, TGA and DSC techniques were employed to monitor and confirm the phase stability of DPC-HH crystals and ferro-para transformations occur in the DPC crystal system.