HoCH2O4 crystallizes in the monoclinic P2_1/c space group. Ho(1) is bonded in a 9-coordinate geometry to one O(3), two equivalent O(1), three equivalent O(2), and three equivalent O(4) atoms. The Ho(1)-O(3) bond length is 2.45 Å. There is one shorter (2.43 Å) and one longer (2.77 Å) Ho(1)-O(1) bond length. There are a spread of Ho(1)-O(2) bond distances ranging from 2.35-2.40 Å. There are a spread of Ho(1)-O(4) bond distances ranging from 2.32-2.37 Å. C(1) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(3) atom. The C(1)-O(1) bond length is 1.27 Å. The C(1)-O(3) bond length is 1.26 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(2) atom. The H(1)-O(2) bond length is 0.98 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(4) atom. The H(2)-O(4) bond length is 0.97 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 Ho(1) and one C(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to three equivalent Ho(1) and one H(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Ho(1) and one C(1) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to three equivalent Ho(1) and one H(2) atom. Linkers: 2 [O]C(=O)C([O])=O. Metal clusters: 4 [Ho]. The MOF has largest included sphere 1.35 A, density 5.05 g/cm3, surface area 821.95 m2/g, accessible volume 0.02 cm3/g