RbC4H3S(NO)2 crystallizes in the monoclinic C2/m space group. Rb(1) is bonded in a 4-coordinate geometry to four equivalent O(1) atoms. There are two shorter (2.97 Å) and two longer (2.98 Å) Rb(1)-O(1) bond lengths. There are three inequivalent C sites. In the first C site, C(1) is bonded in a distorted trigonal planar geometry to two equivalent N(1) and one S(1) atom. Both C(1)-N(1) bond lengths are 1.36 Å. The C(1)-S(1) bond length is 1.69 Å. In the second C site, C(2) is bonded in a distorted trigonal planar geometry to one C(3), one N(1), and one O(1) atom. The C(2)-C(3) bond length is 1.40 Å. The C(2)-N(1) bond length is 1.40 Å. The C(2)-O(1) bond length is 1.28 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to two equivalent C(2) and one H(2) atom. The C(3)-H(2) bond length is 1.09 Å. N(1) is bonded in a trigonal planar geometry to one C(1), one C(2), and one H(1) atom. The N(1)-H(1) bond length is 1.05 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one N(1) and one O(1) atom. The H(1)-O(1) bond length is 1.69 Å. In the second H site, H(2) is bonded in a single-bond geometry to one C(3) atom. S(1) is bonded in a distorted single-bond geometry to one C(1) atom. O(1) is bonded in a distorted single-bond geometry to two equivalent Rb(1), one C(2), and one H(1) atom. Linkers: 2 O=C1[CH]C(=O)NC(=S)N1. Metal clusters: 2 [Rb]. The MOF has largest included sphere 1.55 A, density 2.25 g/cm3, surface area 3159.60 m2/g, accessible volume 0.07 cm3/g