GdC2O5 crystallizes in the orthorhombic Amm2 space group. Gd(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), two equivalent O(4), and four equivalent O(1) atoms. The Gd(1)-O(2) bond length is 2.42 Å. The Gd(1)-O(3) bond length is 2.41 Å. Both Gd(1)-O(4) bond lengths are 2.46 Å. There are two shorter (2.43 Å) and two longer (2.44 Å) Gd(1)-O(1) bond lengths. There are three inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(4) and two equivalent O(1) atoms. The C(1)-O(4) bond length is 1.29 Å. Both C(1)-O(1) bond lengths are 1.27 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to two equivalent O(2) atoms. Both C(2)-O(2) bond lengths are 1.25 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to two equivalent O(3) atoms. Both C(3)-O(3) bond lengths are 1.26 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Gd(1) and one C(1) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Gd(1) and one C(2) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Gd(1) and one C(3) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to two equivalent Gd(1) and one C(1) atom. Linkers: 1 [O]C(=O)C([O])=O. Metal clusters: 2 [Gd]. The MOF has largest included sphere 4.39 A, density 3.03 g/cm3, surface area 1577.24 m2/g, accessible volume 0.09 cm3/g