KYH8(CO3)4 crystallizes in the tetragonal I4_1/a space group. K(1) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(3) atoms. All K(1)-O(2) bond lengths are 2.79 Å. All K(1)-O(3) bond lengths are 2.97 Å. Y(1) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(2) atoms. All Y(1)-O(1) bond lengths are 2.35 Å. All Y(1)-O(2) bond lengths are 2.39 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 1.27 Å. The C(1)-O(2) bond length is 1.26 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to 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 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(2) is bonded in a distorted single-bond geometry to one K(1), one Y(1), and one C(1) atom. In the second O site, O(3) is bonded in a water-like geometry to one K(1), one H(1), and one H(2) atom. In the third O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Y(1) and one C(1) atom. Linkers: 4 [O]C(=O)C([O])=O. Metal clusters: 2 [K] ,2 [Y]. The MOF has largest included sphere 1.52 A, density 2.13 g/cm3, surface area 2324.19 m2/g, accessible volume 0.07 cm3/g