KC3N4H3O5 crystallizes in the orthorhombic Pca2_1 space group. K(1) is bonded in a 9-coordinate geometry to two equivalent N(1), one O(2), one O(3), one O(4), two equivalent O(1), and two equivalent O(5) atoms. There is one shorter (2.95 Å) and one longer (3.21 Å) K(1)-N(1) bond length. The K(1)-O(2) bond length is 3.01 Å. The K(1)-O(3) bond length is 3.20 Å. The K(1)-O(4) bond length is 2.83 Å. There is one shorter (2.89 Å) and one longer (3.13 Å) K(1)-O(1) bond length. There is one shorter (2.68 Å) and one longer (2.69 Å) K(1)-O(5) bond length. There are three inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one N(1), one N(2), and one H(3) atom. The C(1)-N(1) bond length is 1.36 Å. The C(1)-N(2) bond length is 1.35 Å. The C(1)-H(3) bond length is 1.09 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one C(3), one N(2), and one N(3) atom. The C(2)-C(3) bond length is 1.41 Å. The C(2)-N(2) bond length is 1.35 Å. The C(2)-N(3) bond length is 1.42 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to one C(2), one N(1), and one N(4) atom. The C(3)-N(1) bond length is 1.35 Å. The C(3)-N(4) bond length is 1.43 Å. There are four inequivalent N sites. In the first N site, N(2) is bonded in a distorted water-like geometry to one C(1) and one C(2) atom. In the second N site, N(3) is bonded in a trigonal planar geometry to one C(2), one O(1), and one O(2) atom. The N(3)-O(1) bond length is 1.25 Å. The N(3)-O(2) bond length is 1.25 Å. In the third N site, N(4) is bonded in a trigonal planar geometry to one C(3), one O(3), and one O(4) atom. The N(4)-O(3) bond length is 1.24 Å. The N(4)-O(4) bond length is 1.26 Å. In the fourth N site, N(1) is bonded in a distorted water-like geometry to two equivalent K(1), one C(1), and one C(3) atom. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(5) atom. The H(1)-O(5) bond length is 0.98 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(5) atom. The H(2)-O(5) bond length is 1.00 Å. In the third H site, H(3) is bonded in a single-bond geometry to one C(1) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent K(1) and one N(3) atom. In the second O site, O(5) is bonded in a distorted water-like geometry to two equivalent K(1), one H(1), and one H(2) atom. In the third O site, O(2) is bonded in a single-bond geometry to one K(1) and one N(3) atom. In the fourth O site, O(3) is bonded in a single-bond geometry to one K(1) and one N(4) atom. In the fifth O site, O(4) is bonded in a distorted single-bond geometry to one K(1) and one N(4) atom. Linkers: 4 O=[N+]([O-])C1=C([N+](=O)[O-])N=C[N]1. Metal clusters: 4 [K]. The MOF has largest included sphere 1.45 A, density 1.84 g/cm3, surface area 2891.43 m2/g, accessible volume 0.04 cm3/g