A new lithium zinc orthophosphate, δ I -LiZnPO 4 , was synthesized from aqueous solution. Information from powder diffraction, using synchrotron radiation, and 31 P MAS NMR spectroscopy allowed determination of the structure. The structure is orthorhombic (a = 10.0193(1), b = 4.9657(1), c = 6.6746(1) Å space group Pna2 1 , No. 33, Z = 4. The structure may be seen as built from corner-sharing ZnO 4- and PO 4- tetrahedra forming a cristobalite-type framework structure. The lithium ions are 4-coordinated and situated in the 6-ring channels. The thermal transformations were investigated by thermogravimetric measurements (TG), differential thermal analysis (DTA), and high-temperature powder diffraction (HT-PXD). A transformation at ∼575°C is clearly visible on the Guinier Simon film (HT-PXD). This transformation is characterized by some disappearing lines in the powder pattern. The high-temperature polymorph of δ I- LiZnPO 4 is named δ II- LiZnPO 4 . Phase transformations at ∼730 and δ1003°C are observed by HT-PXD and DTA, respectively. These observations are designated to the transformation to β-LiZnPO 4 and from β- to γ-LiZnPO 4 .