K2C9H6SO10H2O crystallizes in the monoclinic P2_1/c space group. The structure consists of four water molecules inside a K2C9H6SO10 framework. In the K2C9H6SO10 framework, there are two inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(7), and one O(8) atom. The K(1)-O(3) bond length is 2.91 Å. The K(1)-O(4) bond length is 2.66 Å. The K(1)-O(7) bond length is 2.66 Å. The K(1)-O(8) bond length is 2.69 Å. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(11), one O(2), one O(6), one O(7), and two equivalent O(9) atoms. The K(2)-O(11) bond length is 2.79 Å. The K(2)-O(2) bond length is 2.90 Å. The K(2)-O(6) bond length is 2.73 Å. The K(2)-O(7) bond length is 2.65 Å. There is one shorter (2.77 Å) and one longer (2.82 Å) K(2)-O(9) bond length. There are nine inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one C(2), one C(6), and one C(7) atom. The C(1)-C(2) bond length is 1.42 Å. The C(1)-C(6) bond length is 1.40 Å. The C(1)-C(7) bond length is 1.51 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one C(1), one C(3), and one C(8) atom. The C(2)-C(3) bond length is 1.40 Å. The C(2)-C(8) bond length is 1.52 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to one C(2), one C(4), and one H(7) atom. The C(3)-C(4) bond length is 1.39 Å. The C(3)-H(7) bond length is 1.09 Å. In the fourth C site, C(4) is bonded in a trigonal planar geometry to one C(3), one C(5), and one C(9) atom. The C(4)-C(5) bond length is 1.41 Å. The C(4)-C(9) bond length is 1.50 Å. In the fifth C site, C(5) is bonded in a trigonal planar geometry to one C(4), one C(6), and one S(1) atom. The C(5)-C(6) bond length is 1.39 Å. The C(5)-S(1) bond length is 1.79 Å. In the sixth C site, C(6) is bonded in a distorted single-bond geometry to one C(1), one C(5), and one H(8) atom. The C(6)-H(8) bond length is 1.09 Å. In the seventh C site, C(7) is bonded in a bent 120 degrees geometry to one C(1), one O(1), and one O(2) atom. The C(7)-O(1) bond length is 1.26 Å. The C(7)-O(2) bond length is 1.29 Å. In the eighth C site, C(8) is bonded in a distorted bent 120 degrees geometry to one C(2), one O(3), and one O(4) atom. The C(8)-O(3) bond length is 1.32 Å. The C(8)-O(4) bond length is 1.24 Å. In the ninth C site, C(9) is bonded in a distorted bent 120 degrees geometry to one C(4), one O(5), and one O(6) atom. The C(9)-O(5) bond length is 1.32 Å. The C(9)-O(6) bond length is 1.24 Å. There are six inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to one O(2) and one O(3) atom. The H(1)-O(2) bond length is 1.18 Å. The H(1)-O(3) bond length is 1.20 Å. In the second H site, H(2) is bonded in a linear geometry to one O(1) and one O(5) atom. The H(2)-O(1) bond length is 1.54 Å. The H(2)-O(5) bond length is 1.04 Å. In the third H site, H(5) is bonded in a single-bond geometry to one O(11) atom. The H(5)-O(11) bond length is 0.99 Å. In the fourth H site, H(6) is bonded in a single-bond geometry to one O(11) atom. The H(6)-O(11) bond length is 0.99 Å. In the fifth H site, H(7) is bonded in a single-bond geometry to one C(3) atom. In the sixth H site, H(8) is bonded in a single-bond geometry to one C(6) atom. S(1) is bonded in a distorted trigonal non-coplanar geometry to one C(5), one O(7), one O(8), and one O(9) atom. The S(1)-O(7) bond length is 1.47 Å. The S(1)-O(8) bond length is 1.46 Å. The S(1)-O(9) bond length is 1.48 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a water-like geometry to one C(7) and one H(2) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(2), one C(7), and one H(1) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one K(1), one C(8), and one H(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1) and one C(8) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one C(9) and one H(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one K(2) and one C(9) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one K(1), one K(2), and one S(1) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(1) and one S(1) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to two equivalent K(2) and one S(1) atom. In the tenth O site, O(11) is bonded in a water-like geometry to one K(2), one H(5), and one H(6) atom. Linkers: 4 [O]C(=O)c1cc(C(=O)O)c(S([O])([O])[O])cc1C(=O)O. Metal clusters: 8 [K]. The MOF has largest included sphere 1.38 A, density 1.94 g/cm3, surface area 1863.44 m2/g, accessible volume 0.03 cm3/g