CaH4(C3O2)3 crystallizes in the triclinic P-1 space group. Ca(1) is bonded to one O(1), one O(5), one O(6), two equivalent O(2), and two equivalent O(4) atoms to form distorted edge-sharing CaO7 pentagonal bipyramids. The Ca(1)-O(1) bond length is 2.42 Å. The Ca(1)-O(5) bond length is 2.38 Å. The Ca(1)-O(6) bond length is 2.39 Å. There is one shorter (2.41 Å) and one longer (2.46 Å) Ca(1)-O(2) bond length. There is one shorter (2.40 Å) and one longer (2.55 Å) Ca(1)-O(4) bond length. There are nine inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one C(3), one C(6), and one C(8) atom. The C(1)-C(3) bond length is 1.40 Å. The C(1)-C(6) bond length is 1.50 Å. The C(1)-C(8) bond length is 1.40 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one C(5), one C(7), and one C(8) atom. The C(2)-C(5) bond length is 1.40 Å. The C(2)-C(7) bond length is 1.49 Å. The C(2)-C(8) bond length is 1.40 Å. In the third C site, C(3) is bonded in a distorted trigonal planar geometry to one C(1), one C(9), and one H(2) atom. The C(3)-C(9) bond length is 1.40 Å. The C(3)-H(2) bond length is 1.09 Å. In the fourth C site, C(4) is bonded in a distorted bent 120 degrees geometry to one C(9), one O(3), and one O(5) atom. The C(4)-C(9) bond length is 1.48 Å. The C(4)-O(3) bond length is 1.32 Å. The C(4)-O(5) bond length is 1.25 Å. In the fifth C site, C(5) is bonded in a distorted single-bond geometry to one C(2), one C(9), and one H(3) atom. The C(5)-C(9) bond length is 1.40 Å. The C(5)-H(3) bond length is 1.09 Å. In the sixth C site, C(6) is bonded in a distorted bent 120 degrees geometry to one C(1), one O(1), and one O(6) atom. The C(6)-O(1) bond length is 1.29 Å. The C(6)-O(6) bond length is 1.27 Å. In the seventh C site, C(7) is bonded in a distorted bent 120 degrees geometry to one C(2), one O(2), and one O(4) atom. The C(7)-O(2) bond length is 1.28 Å. The C(7)-O(4) bond length is 1.28 Å. In the eighth C site, C(8) is bonded in a distorted single-bond geometry to one C(1), one C(2), and one H(4) atom. The C(8)-H(4) bond length is 1.09 Å. In the ninth C site, C(9) is bonded in a trigonal planar geometry to one C(3), one C(4), and one C(5) atom. There are four inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to one O(1) and one O(3) atom. The H(1)-O(1) bond length is 1.54 Å. The H(1)-O(3) bond length is 1.02 Å. In the second H site, H(2) is bonded in a single-bond geometry to one C(3) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(5) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(8) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Ca(1), one C(6), and one H(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one C(7) atom. In the third O site, O(3) is bonded in a water-like geometry to one C(4) and one H(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one C(7) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Ca(1) and one C(4) atom. In the sixth O site, O(6) is bonded in an L-shaped geometry to one Ca(1) and one C(6) atom. Linkers: 2 [O]C(=O)c1cc(C([O])=O)cc(C(=O)O)c1. Metal clusters: 2 [Ca]. The MOF has largest included sphere 3.87 A, density 1.54 g/cm3, surface area 3467.52 m2/g, accessible volume 0.20 cm3/g