NaCN4H4O3 crystallizes in the triclinic P-1 space group. Na(1) is bonded to one N(4), one O(1), two equivalent O(2), and two equivalent O(3) atoms to form edge-sharing NaNO5 octahedra. The Na(1)-N(4) bond length is 2.45 Å. The Na(1)-O(1) bond length is 2.39 Å. There is one shorter (2.35 Å) and one longer (2.40 Å) Na(1)-O(2) bond length. There is one shorter (2.39 Å) and one longer (2.51 Å) Na(1)-O(3) bond length. C(1) is bonded in a distorted water-like geometry to one C(1), one N(1), and one N(4) atom. The C(1)-C(1) bond length is 1.44 Å. The C(1)-N(1) bond length is 1.37 Å. The C(1)-N(4) bond length is 1.34 Å. There are four inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal planar geometry to one C(1), one N(2), and one O(1) atom. The N(1)-N(2) bond length is 1.35 Å. The N(1)-O(1) bond length is 1.30 Å. In the second N site, N(2) is bonded in a water-like geometry to one N(1) and one N(3) atom. The N(2)-N(3) bond length is 1.32 Å. In the third N site, N(3) is bonded in a 2-coordinate geometry to one N(2) and one N(4) atom. The N(3)-N(4) bond length is 1.34 Å. In the fourth N site, N(4) is bonded in a distorted trigonal planar geometry to one Na(1), one C(1), and one N(3) atom. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) and one O(2) atom. The H(1)-O(1) bond length is 1.81 Å. The H(1)-O(2) bond length is 0.99 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(1) and one O(2) atom. The H(2)-O(1) bond length is 1.73 Å. The H(2)-O(2) bond length is 0.99 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(3) atom. The H(3)-O(3) bond length is 0.99 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(3) atom. The H(4)-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 4-coordinate geometry to one Na(1), one N(1), one H(1), and one H(2) atom. In the second O site, O(2) is bonded in a distorted water-like geometry to two equivalent Na(1), one H(1), and one H(2) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to two equivalent Na(1), one H(3), and one H(4) atom. Linkers: 1 [O]n1nnnc1-c1nnnn1[O]. Metal clusters: 2 [Na]. The MOF has largest included sphere 1.75 A, density 1.76 g/cm3, surface area 3335.73 m2/g, accessible volume 0.10 cm3/g