KC2PN3H3O4 crystallizes in the monoclinic P2_1/c space group. K(1) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), and two equivalent O(2) atoms. The K(1)-O(1) bond length is 2.62 Å. The K(1)-O(3) bond length is 2.83 Å. The K(1)-O(4) bond length is 2.70 Å. There is one shorter (2.74 Å) and one longer (2.92 Å) K(1)-O(2) bond length. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one N(1), one N(3), and one O(3) atom. The C(1)-N(1) bond length is 1.37 Å. The C(1)-N(3) bond length is 1.36 Å. The C(1)-O(3) bond length is 1.26 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one N(1), one N(2), and one O(4) atom. The C(2)-N(1) bond length is 1.38 Å. The C(2)-N(2) bond length is 1.36 Å. The C(2)-O(4) bond length is 1.25 Å. P(1) is bonded in a tetrahedral geometry to one N(2), one N(3), one O(1), and one O(2) atom. The P(1)-N(2) bond length is 1.70 Å. The P(1)-N(3) bond length is 1.70 Å. The P(1)-O(1) bond length is 1.49 Å. The P(1)-O(2) bond length is 1.52 Å. There are three inequivalent N sites. In the first N site, N(2) is bonded in a trigonal planar geometry to one C(2), one P(1), and one H(1) atom. The N(2)-H(1) bond length is 1.05 Å. In the second N site, N(3) is bonded in a trigonal planar geometry to one C(1), one P(1), and one H(3) atom. The N(3)-H(3) bond length is 1.05 Å. In the third N site, N(1) is bonded in a trigonal planar geometry to one C(1), one C(2), and one H(2) atom. The N(1)-H(2) bond length is 1.04 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one N(2) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one N(1) atom. In the third H site, H(3) is bonded in a distorted single-bond geometry to one N(3) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one K(1) and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one K(1) and one C(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1) and one C(2) atom. Linkers: 4 [O]P1(=O)NC(=O)NC(=O)N1. Metal clusters: 4 [K]. The MOF has largest included sphere 1.47 A, density 2.01 g/cm3, surface area 1782.36 m2/g, accessible volume 0.02 cm3/g