Mn-doped beta-tricalcium phosphate was prepared by solid state reaction at 1100 degrees C. The crystal structure of Ca2.85Mn0.15(PO4)(2), was determined by single crystal X-ray diffraction and found to be rhombohedral, R3c. Unit cell parameters are: a = 10.3419(3); c = 37.025(3) angstrom (hexagonal setting), Z = 21. Structure refinement data show that from the five Ca positions the Ca(4) site is only half filled and that the Mn2+ ions occupy the hexacoordinated Ca(5) site solely. EPR spectroscopy reveals that manganese in solid solutions Ca3-xMnx(PO4)(2) (x = 0.1; 0.28; 0.6) is divalent and supports the structure refinement results that Mn occupies the Ca(5) site with a geometry very near to a regular octahedron. (C) 2007 Elsevier Ltd. All rights reserved.