CaNi5H crystallizes in the monoclinic Cm space group. Ca(1) is bonded in a distorted single-bond geometry to three equivalent Ni(2), four equivalent Ni(3), and one H(1) atom. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a single-bond geometry to two equivalent Ni(3) and one H(1) atom. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to three equivalent Ca(1), two equivalent Ni(3), and four equivalent Ni(4) atoms. In the third Ni site, Ni(3) is bonded to four equivalent Ca(1), two equivalent Ni(1), two equivalent Ni(2), and four equivalent Ni(4) atoms to form distorted NiCa4Ni8 cuboctahedra that share corners with eight equivalent Ni(3)Ca4Ni8 cuboctahedra, corners with three equivalent H(1)CaNi3 trigonal pyramids, edges with two equivalent Ni(3)Ca4Ni8 cuboctahedra, edges with two equivalent H(1)CaNi3 trigonal pyramids, faces with two equivalent Ni(3)Ca4Ni8 cuboctahedra, and  a faceface with one H(1)CaNi3 trigonal pyramid. In the fourth Ni site, Ni(4) is bonded in a single-bond geometry to two equivalent Ni(2), two equivalent Ni(3), and one H(1) atom. H(1) is bonded to one Ca(1), one Ni(1), and two equivalent Ni(4) atoms to form HCaNi3 trigonal pyramids that share corners with three equivalent Ni(3)Ca4Ni8 cuboctahedra, edges with two equivalent Ni(3)Ca4Ni8 cuboctahedra, and  a faceface with one Ni(3)Ca4Ni8 cuboctahedra.
CaNi5H crystallizes in the monoclinic Cm space group. Ca(1) is bonded in a distorted single-bond geometry to three equivalent Ni(2), four equivalent Ni(3), and one H(1) atom. There is one shorter (2.86 Å) and two longer (2.90 Å) Ca(1)-Ni(2) bond lengths. There are two shorter (3.13 Å) and two longer (3.29 Å) Ca(1)-Ni(3) bond lengths. The Ca(1)-H(1) bond length is 2.22 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a single-bond geometry to two equivalent Ni(3) and one H(1) atom. There is one shorter (2.39 Å) and one longer (2.44 Å) Ni(1)-Ni(3) bond length. The Ni(1)-H(1) bond length is 1.64 Å. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to three equivalent Ca(1), two equivalent Ni(3), and four equivalent Ni(4) atoms. There is one shorter (2.41 Å) and one longer (2.43 Å) Ni(2)-Ni(3) bond length. There are two shorter (2.42 Å) and two longer (2.49 Å) Ni(2)-Ni(4) bond lengths. In the third Ni site, Ni(3) is bonded to four equivalent Ca(1), two equivalent Ni(1), two equivalent Ni(2), and four equivalent Ni(4) atoms to form distorted NiCa4Ni8 cuboctahedra that share corners with eight equivalent Ni(3)Ca4Ni8 cuboctahedra, corners with three equivalent H(1)CaNi3 trigonal pyramids, edges with two equivalent Ni(3)Ca4Ni8 cuboctahedra, edges with two equivalent H(1)CaNi3 trigonal pyramids, faces with two equivalent Ni(3)Ca4Ni8 cuboctahedra, and  a faceface with one H(1)CaNi3 trigonal pyramid. There are two shorter (2.47 Å) and two longer (2.50 Å) Ni(3)-Ni(4) bond lengths. In the fourth Ni site, Ni(4) is bonded in a single-bond geometry to two equivalent Ni(2), two equivalent Ni(3), and one H(1) atom. The Ni(4)-H(1) bond length is 1.61 Å. H(1) is bonded to one Ca(1), one Ni(1), and two equivalent Ni(4) atoms to form HCaNi3 trigonal pyramids that share corners with three equivalent Ni(3)Ca4Ni8 cuboctahedra, edges with two equivalent Ni(3)Ca4Ni8 cuboctahedra, and  a faceface with one Ni(3)Ca4Ni8 cuboctahedra.