U5(PO4)4 crystallizes in the monoclinic C2/m space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a distorted pentagonal planar geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. The U(1)-O(3) bond length is 2.22 Å. There is one shorter (2.35 Å) and one longer (2.51 Å) U(1)-O(1) bond length. There is one shorter (2.38 Å) and one longer (2.48 Å) U(1)-O(2) bond length. In the second U site, U(2) is bonded in a square co-planar geometry to four equivalent O(4) atoms. All U(2)-O(4) bond lengths are 2.27 Å. P(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. The P(1)-O(1) bond length is 1.55 Å. The P(1)-O(2) bond length is 1.51 Å. The P(1)-O(3) bond length is 1.55 Å. The P(1)-O(4) bond length is 1.53 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent U(1) and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent U(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one U(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one U(2) and one P(1) atom. Linkers: 8 [O]P([O])([O])=O. Metal clusters: 10 [U]. The MOF has largest included sphere 5.76 A, density 3.74 g/cm3, surface area 1108.41 m2/g, accessible volume 0.13 cm3/g