A three-dimensional manganese（Ⅱ）-substituted aluminum phosphate, Mn3Al6（PO4）12·4tren·11H2O[tren is tris（2-aminoethyl）amine], was synthesized hydrothermally. Its structure was determined by single-crystal X-ray diffraction analysis and further characterized by X-ray powder diffraction, ICP, TG analyses and magnetic susceptibility measurements. It crystallizes in the cubicsystem, space group I-43m（No. 217） with a=1.683 51（4）nm, V=4.771 4（2） nm3, Z=2, R1=0.043 9 and wR2=0.132 4[I>2σ（I）]. The open framework built up from strict alternation of TO4/AlO4 and PO4 tetrahedra through corner-sharing vertex oxygen atoms. It contains 12-membered ring channels. The Mn atoms of the framework are bivalence proved by magnetic susceptibility measurements.
