CaC8H6SO8 crystallizes in the monoclinic P2_1/m space group. Ca(1) is bonded in a distorted pentagonal bipyramidal geometry to one O(2), one O(3), one O(6), two equivalent O(4), and two equivalent O(5) atoms. The Ca(1)-O(2) bond length is 2.44 Å. The Ca(1)-O(3) bond length is 2.44 Å. The Ca(1)-O(6) bond length is 2.30 Å. Both Ca(1)-O(4) bond lengths are 2.50 Å. Both Ca(1)-O(5) bond lengths are 2.32 Å. There are eight inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one C(2), one O(1), and one O(3) atom. The C(1)-C(2) bond length is 1.48 Å. The C(1)-O(1) bond length is 1.33 Å. The C(1)-O(3) bond length is 1.24 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(7) atom. The C(2)-C(3) bond length is 1.40 Å. The C(2)-C(7) bond length is 1.40 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to one C(2) and one H(3) atom. The C(3)-H(3) bond length is 1.09 Å. In the fourth C site, C(4) is bonded in a distorted single-bond geometry to one C(5) and one H(4) atom. The C(4)-C(5) bond length is 1.40 Å. The C(4)-H(4) bond length is 1.09 Å. In the fifth C site, C(5) is bonded in a trigonal planar geometry to one C(4), one C(6), and one C(8) atom. The C(5)-C(6) bond length is 1.41 Å. The C(5)-C(8) bond length is 1.51 Å. In the sixth C site, C(6) is bonded in a trigonal planar geometry to one C(5), one C(7), and one S(1) atom. The C(6)-C(7) bond length is 1.39 Å. The C(6)-S(1) bond length is 1.78 Å. In the seventh C site, C(7) is bonded in a distorted single-bond geometry to one C(2), one C(6), and one H(5) atom. The C(7)-H(5) bond length is 1.09 Å. In the eighth C site, C(8) is bonded in a distorted bent 120 degrees geometry to one C(5) and two equivalent O(4) atoms. Both C(8)-O(4) bond lengths are 1.27 Å. There are five inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to one O(1) and one O(2) atom. The H(1)-O(1) bond length is 1.04 Å. The H(1)-O(2) bond length is 1.54 Å. In the second H site, H(2) is bonded in a distorted single-bond geometry to one O(2) and one O(4) atom. The H(2)-O(2) bond length is 1.01 Å. The H(2)-O(4) bond length is 1.66 Å. In the third H site, H(3) is bonded in a single-bond geometry to one C(3) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(4) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(7) atom. S(1) is bonded in a distorted trigonal non-coplanar geometry to one C(6), one O(6), and two equivalent O(5) atoms. The S(1)-O(6) bond length is 1.47 Å. Both S(1)-O(5) bond lengths are 1.46 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a water-like geometry to one C(1) and one H(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one H(1), and two equivalent H(2) atoms. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Ca(1) and one C(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one C(8), and one H(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Ca(1) and one S(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Ca(1) and one S(1) atom. Linkers: 2 [O]C(=O)c1ccc(C(=O)O)cc1S([O])([O])[O]. Metal clusters: 2 [Ca]. RCSR code: lon. The MOF has largest included sphere 1.79 A, density 1.89 g/cm3, surface area 3467.10 m2/g, accessible volume 0.13 cm3/g