ErC5NHO4(CH)2 crystallizes in the tetragonal I4_1/a space group. The structure consists of thirty-two 02329_fluka molecules inside a ErC5NHO4 framework. In the ErC5NHO4 framework, Er(1) is bonded in a distorted pentagonal planar geometry to one N(1), one O(1), one O(2), one O(3), and one O(4) atom. The Er(1)-N(1) bond length is 2.44 Å. The Er(1)-O(1) bond length is 2.37 Å. The Er(1)-O(2) bond length is 2.40 Å. The Er(1)-O(3) bond length is 2.33 Å. The Er(1)-O(4) bond length is 2.34 Å. There are five inequivalent C sites. In the first C site, C(1) is bonded in a distorted trigonal planar geometry to one C(2), one C(6), and one N(1) atom. The C(1)-C(2) bond length is 1.37 Å. The C(1)-C(6) bond length is 1.52 Å. The C(1)-N(1) bond length is 1.34 Å. In the second C site, C(2) is bonded in a distorted single-bond geometry to one C(1) and one H(1) atom. The C(2)-H(1) bond length is 0.93 Å. In the third C site, C(5) is bonded in a distorted single-bond geometry to one N(1) atom. The C(5)-N(1) bond length is 1.33 Å. In the fourth C site, C(6) is bonded in a distorted bent 120 degrees geometry to one C(1), one O(1), and one O(2) atom. The C(6)-O(1) bond length is 1.24 Å. The C(6)-O(2) bond length is 1.27 Å. In the fifth C site, C(7) is bonded in a distorted bent 120 degrees geometry to one O(3) and one O(4) atom. The C(7)-O(3) bond length is 1.25 Å. The C(7)-O(4) bond length is 1.27 Å. N(1) is bonded in a trigonal planar geometry to one Er(1), one C(1), and one C(5) atom. H(1) is bonded in a single-bond geometry to one C(2) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Er(1) and one C(6) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Er(1) and one C(6) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Er(1) and one C(7) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Er(1) and one C(7) atom. Linkers: 16 [O]C(=O)c1cccc(C([O])=O)n1. Metal clusters: 16 [Er]. The MOF has largest included sphere 8.81 A, density 1.16 g/cm3, surface area 2922.70 m2/g, accessible volume 0.55 cm3/g