CsCH2O3 crystallizes in the monoclinic P2_1/c space group. Cs(1) is bonded in a 12-coordinate geometry to one H(2), two equivalent H(1), two equivalent O(2), three equivalent O(3), and four equivalent O(1) atoms. The Cs(1)-H(2) bond length is 3.35 Å. There is one shorter (3.11 Å) and one longer (3.26 Å) Cs(1)-H(1) bond length. There is one shorter (3.13 Å) and one longer (3.19 Å) Cs(1)-O(2) bond length. There are a spread of Cs(1)-O(3) bond distances ranging from 3.19-3.31 Å. There are a spread of Cs(1)-O(1) bond distances ranging from 3.19-3.32 Å. C(1) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(2) atom. The C(1)-O(1) bond length is 1.26 Å. The C(1)-O(2) bond length is 1.28 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to two equivalent Cs(1) and one O(3) atom. The H(1)-O(3) bond length is 0.99 Å. In the second H site, H(2) is bonded in a single-bond geometry to one Cs(1) and one O(3) atom. The H(2)-O(3) bond length is 0.99 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to four equivalent Cs(1) and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Cs(1) and one C(1) atom. In the third O site, O(3) is bonded in a water-like geometry to three equivalent Cs(1), one H(1), and one H(2) atom. Linkers: 2 [O]C(=O)C([O])=O. Metal clusters: 4 [Cs]. The MOF has largest included sphere 1.54 A, density 3.29 g/cm3, surface area 2183.69 m2/g, accessible volume 0.03 cm3/g