K 2 ZnH 4 and its deuteride were prepared by a solid state reaction between stoichiometric amounts of KH (KD) and Zn metal powders at 650 K and 80 bar hydrogen (deuterium) pressure, and characterized by X-ray and neutron powder diffraction. They crystallize with the orthorhombic βK 2 SO 4 structure type, space group Pnma (No. 62), Z = 4, cell parametersa = 7.7601(5), b = 5.8636(4),c = 10.2832(7) (hydride);a = 7.7579(4),b = 5.8631(3),c = 10.2813(5) (deuteride). Zinc is tetrahedrally coordinated by deuterium with bond distances in the range of 1.632(4) to 1.665(4) and bond angles in the range 108.0° to 112.7°. K 2 ZnD 4 decomposes in 1 bar D 2 at 580(10) K to KD and Zn.