From abstract: "The report describes the complete structure of barium hydrogen phosphate, Ba HPO4, as determined by means of x-ray diffraction. The crystal is orthorhombic, with cell dimensions given by a=5.71 A b=7.05 A c=4.61 A. The calculated density is 4.15gm/cm[^]3 for two molecules in the unit cell. The space group is C[subscript]2v[superscript]7-pmn. The barium, phosphorus, and two sets of oxygen lie in the plane of symmetry. The third set of oxygens are in general positions. Parameters for these atoms have been found, and interatomic distances calculated. The positions of the hydrogens are indicated by the characteristics O-H-O distance (2.58A) between two oxygens."