HoC2PH6O7 crystallizes in the orthorhombic Pnma space group. Ho(1) is bonded to one O(2), one O(4), one O(5), two equivalent O(1), and two equivalent O(3) atoms to form distorted HoO7 pentagonal bipyramids that share corners with three equivalent P(1)CO3 tetrahedra. The Ho(1)-O(2) bond length is 2.19 Å. The Ho(1)-O(4) bond length is 2.28 Å. The Ho(1)-O(5) bond length is 2.33 Å. Both Ho(1)-O(1) bond lengths are 2.45 Å. Both Ho(1)-O(3) bond lengths are 2.22 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to two equivalent O(1) atoms. Both C(1)-O(1) bond lengths are 1.28 Å. In the second C site, C(2) is bonded in a distorted water-like geometry to one P(1) and two equivalent H(1) atoms. The C(2)-P(1) bond length is 1.84 Å. Both C(2)-H(1) bond lengths are 1.10 Å. P(1) is bonded to one C(2), one O(2), and two equivalent O(3) atoms to form PCO3 tetrahedra that share corners with three equivalent Ho(1)O7 pentagonal bipyramids. The P(1)-O(2) bond length is 1.53 Å. Both P(1)-O(3) bond lengths are 1.54 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(2) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one O(1) and one O(4) atom. The H(2)-O(1) bond length is 1.67 Å. The H(2)-O(4) bond length is 1.00 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(5) atom. The H(3)-O(5) bond length is 0.98 Å. There are five inequivalent O sites. In the first O site, O(5) is bonded in a distorted water-like geometry to one Ho(1) and two equivalent H(3) atoms. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Ho(1), one C(1), and one H(2) atom. In the third O site, O(2) is bonded in a bent 150 degrees geometry to one Ho(1) and one P(1) atom. In the fourth O site, O(3) is bonded in a bent 150 degrees geometry to one Ho(1) and one P(1) atom. In the fifth O site, O(4) is bonded in a distorted water-like geometry to one Ho(1) and two equivalent H(2) atoms. Linkers: 4 [O]C(=O)CP([O])([O])=O. Metal clusters: 4 [Ho]. The MOF has largest included sphere 1.39 A, density 3.35 g/cm3, surface area 2079.15 m2/g, accessible volume 0.04 cm3/g