RbNiH3(CO2)3 crystallizes in the hexagonal P6_322 space group. Rb(1) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. All Rb(1)-O(1) bond lengths are 2.97 Å. Ni(1) is bonded in an octahedral geometry to six equivalent O(1) atoms. All Ni(1)-O(1) bond lengths are 2.08 Å. C(1) is bonded in a trigonal planar geometry to one H(1) and two equivalent O(1) atoms. The C(1)-H(1) bond length is 1.10 Å. Both C(1)-O(1) bond lengths are 1.27 Å. H(1) is bonded in a single-bond geometry to one C(1) atom. O(1) is bonded in a 3-coordinate geometry to one Rb(1), one Ni(1), and one C(1) atom. Linkers: 6 [O]C=O. Metal clusters: 2 [Rb] ,2 [Ni]. The MOF has largest included sphere 2.54 A, density 2.47 g/cm3, surface area 2592.29 m2/g, accessible volume 0.10 cm3/g