CdC2N4H2O3 crystallizes in the orthorhombic Fdd2 space group. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded in a 6-coordinate geometry to two equivalent N(1), two equivalent N(4), and two equivalent O(1) atoms. Both Cd(1)-N(1) bond lengths are 2.39 Å. Both Cd(1)-N(4) bond lengths are 2.35 Å. Both Cd(1)-O(1) bond lengths are 2.51 Å. In the second Cd site, Cd(2) is bonded in a distorted pentagonal pyramidal geometry to two equivalent N(2), two equivalent O(2), and two equivalent O(3) atoms. Both Cd(2)-N(2) bond lengths are 2.39 Å. Both Cd(2)-O(2) bond lengths are 2.40 Å. Both Cd(2)-O(3) bond lengths are 2.29 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a distorted water-like geometry to one N(1) and one N(4) atom. The C(1)-N(1) bond length is 1.34 Å. The C(1)-N(4) bond length is 1.34 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(2) atom. The C(2)-O(1) bond length is 1.27 Å. The C(2)-O(2) bond length is 1.27 Å. There are four inequivalent N sites. In the first N site, N(1) is bonded in a 3-coordinate geometry to one Cd(1), one C(1), and one N(2) atom. The N(1)-N(2) bond length is 1.33 Å. In the second N site, N(2) is bonded in a trigonal planar geometry to one Cd(2), one N(1), and one N(3) atom. The N(2)-N(3) bond length is 1.32 Å. In the third N site, N(3) is bonded in a distorted trigonal planar geometry to one N(2), one N(4), and one H(1) atom. The N(3)-N(4) bond length is 1.33 Å. The N(3)-H(1) bond length is 1.79 Å. In the fourth N site, N(4) is bonded in a 3-coordinate geometry to one Cd(1), one C(1), and one N(3) atom. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one N(3) and one O(3) atom. The H(1)-O(3) bond length is 1.00 Å. In the second H site, H(2) is bonded in a distorted single-bond geometry to one O(1) and one O(3) atom. The H(2)-O(1) bond length is 1.69 Å. The H(2)-O(3) bond length is 1.00 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Cd(1), one C(2), and one H(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Cd(2) and one C(2) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one Cd(2), one H(1), and one H(2) atom. Linkers: 4 [O]C(=O)C1=NN=N[N]1. Metal clusters: 4 [Cd]. The MOF has largest included sphere 2.92 A, density 2.55 g/cm3, surface area 2393.16 m2/g, accessible volume 0.12 cm3/g