This is a pre-print version of and article that was as: DJ Price, AK Powell, PT Wood, Polyhedron 1999, 18, 2499-2503. The final article can be accessed at http://www.sciencedirect.com/science/article/pii/S0277538799001357 Hydrothermal Crystallisation and X-ray Structure Anhydrous Strontium Oxalate Daniel J. Price, Annie K. Powell and Paul T. Wood School of Chemical Sciences, University of East Anglia, Norwich, NR4 7TJ, UK Abstract— Single crystals of anhydrous strontium oxalate have been prepared by hydrothermal synthesis in the presence of divalent transition metal ions. Strontium is eight coordinate with approximate square antiprismatic geometry. The SrO 8 polyhedra form a 3-dimensional network by sharing edges and vertices. This structure is compared to that of the strontium oxalate hydrates and related calcium minerals weddelite Ca(C 2 O 4 )(H 2 O) 2 and whewellite Ca(C 2 O 4 )(H 2 O). Keywords: strontium; oxalate; hydrothermal synthesis Despite recent advances in the determination of crystal structure from powder diffraction data there are many commonly used inorganic materials for which the structures remain unknown. One such material is anhydrous strontium oxalate, Sr(C 2 O 4 ), whose diverse applications include its use as a component in fireworks [1], as an additive in paint primers [2] and as a reagent in the synthesis of strontium containing high temperature superconductors [3]. The use of hydrothermal conditions at 240 °C has for the first time allowed single crystals, large enough for x-ray structure determination to be obtained. The synthesis and