ErH8(C3O5)2 crystallizes in the orthorhombic Iba2 space group. Er(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(2), one O(3), one O(4), one O(5), one O(6), and one O(8) atom. The Er(1)-O(1) bond length is 2.25 Å. The Er(1)-O(10) bond length is 2.37 Å. The Er(1)-O(2) bond length is 2.31 Å. The Er(1)-O(3) bond length is 2.30 Å. The Er(1)-O(4) bond length is 2.42 Å. The Er(1)-O(5) bond length is 2.35 Å. The Er(1)-O(6) bond length is 2.28 Å. The Er(1)-O(8) bond length is 2.35 Å. There are six inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one O(2) and one O(3) atom. The C(1)-O(2) bond length is 1.28 Å. The C(1)-O(3) bond length is 1.26 Å. In the second C site, C(2) is bonded in a distorted water-like geometry to one H(6) and one O(4) atom. The C(2)-H(6) bond length is 1.10 Å. The C(2)-O(4) bond length is 1.43 Å. In the third C site, C(3) is bonded in a distorted water-like geometry to one H(7) and one O(5) atom. The C(3)-H(7) bond length is 1.10 Å. The C(3)-O(5) bond length is 1.44 Å. In the fourth C site, C(4) is bonded in a distorted bent 120 degrees geometry to one O(6) and one O(7) atom. The C(4)-O(6) bond length is 1.28 Å. The C(4)-O(7) bond length is 1.25 Å. In the fifth C site, C(5) is bonded in a distorted bent 120 degrees geometry to one O(8) and one O(9) atom. The C(5)-O(8) bond length is 1.28 Å. The C(5)-O(9) bond length is 1.26 Å. In the sixth C site, C(6) is bonded in a distorted water-like geometry to one H(8) and one O(10) atom. The C(6)-H(8) bond length is 1.10 Å. The C(6)-O(10) bond length is 1.43 Å. There are eight inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. The H(1)-O(1) bond length is 0.99 Å. In the second H site, H(2) is bonded in a distorted bent 150 degrees geometry to one O(1) and one O(7) atom. The H(2)-O(1) bond length is 1.00 Å. The H(2)-O(7) bond length is 1.63 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(4) and one O(9) atom. The H(3)-O(4) bond length is 1.00 Å. The H(3)-O(9) bond length is 1.70 Å. In the fourth H site, H(4) is bonded in a distorted single-bond geometry to one O(5) and one O(8) atom. The H(4)-O(5) bond length is 1.00 Å. The H(4)-O(8) bond length is 1.70 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(10) and one O(9) atom. The H(5)-O(10) bond length is 1.01 Å. The H(5)-O(9) bond length is 1.71 Å. In the sixth H site, H(6) is bonded in a single-bond geometry to one C(2) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one C(3) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one C(6) atom. There are ten inequivalent O sites. In the first O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Er(1) and one C(1) atom. In the second O site, O(4) is bonded in a 2-coordinate geometry to one Er(1), one C(2), and one H(3) atom. In the third O site, O(5) is bonded in a 3-coordinate geometry to one Er(1), one C(3), and one H(4) atom. In the fourth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Er(1) and one C(4) atom. In the fifth O site, O(7) is bonded in a bent 150 degrees geometry to one C(4) and one H(2) atom. In the sixth O site, O(8) is bonded in a distorted trigonal planar geometry to one Er(1), one C(5), and one H(4) atom. In the seventh O site, O(9) is bonded in a distorted single-bond geometry to one C(5), one H(3), and one H(5) atom. In the eighth O site, O(10) is bonded in a 2-coordinate geometry to one Er(1), one C(6), and one H(5) atom. In the ninth O site, O(1) is bonded in a distorted water-like geometry to one Er(1), one H(1), and one H(2) atom. In the tenth O site, O(2) is bonded in a distorted single-bond geometry to one Er(1) and one C(1) atom. Linkers: 2 [O]C(=O)[C@@H](O)[C@H](O)C([O])=O ,3 [O]C(=O)[C@H](O)[C@@H](O)C([O])=O. Metal clusters: 4 [Er]. The MOF has largest included sphere 1.93 A, density 2.99 g/cm3, surface area 2027.52 m2/g, accessible volume 0.04 cm3/g