CaBi2O4 crystallizes in the orthorhombic Cmcm space group. Ca(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Bi(1) is bonded to one O(2), two equivalent O(3), and three equivalent O(1) atoms to form a mixture of corner and edge-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles range from 0-62°. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and three equivalent Bi(1) atoms to form OCa2Bi3 trigonal bipyramids that share corners with five equivalent O(2)Ca2Bi2 tetrahedra, corners with two equivalent O(1)Ca2Bi3 trigonal bipyramids,  an edgeedge with one O(2)Ca2Bi2 tetrahedra, and edges with five equivalent O(1)Ca2Bi3 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Ca(1) and two equivalent Bi(1) atoms to form OCa2Bi2 tetrahedra that share corners with two equivalent O(2)Ca2Bi2 tetrahedra, corners with ten equivalent O(1)Ca2Bi3 trigonal bipyramids, and edges with two equivalent O(1)Ca2Bi3 trigonal bipyramids. In the third O site, O(3) is bonded in a square co-planar geometry to four equivalent Bi(1) atoms.
CaBi2O4 crystallizes in the orthorhombic Cmcm space group. Ca(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Both Ca(1)-O(2) bond lengths are 2.35 Å. All Ca(1)-O(1) bond lengths are 2.59 Å. Bi(1) is bonded to one O(2), two equivalent O(3), and three equivalent O(1) atoms to form a mixture of corner and edge-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles range from 0-62°. The Bi(1)-O(2) bond length is 2.31 Å. Both Bi(1)-O(3) bond lengths are 2.44 Å. There are two shorter (2.41 Å) and one longer (2.50 Å) Bi(1)-O(1) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and three equivalent Bi(1) atoms to form OCa2Bi3 trigonal bipyramids that share corners with five equivalent O(2)Ca2Bi2 tetrahedra, corners with two equivalent O(1)Ca2Bi3 trigonal bipyramids,  an edgeedge with one O(2)Ca2Bi2 tetrahedra, and edges with five equivalent O(1)Ca2Bi3 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Ca(1) and two equivalent Bi(1) atoms to form OCa2Bi2 tetrahedra that share corners with two equivalent O(2)Ca2Bi2 tetrahedra, corners with ten equivalent O(1)Ca2Bi3 trigonal bipyramids, and edges with two equivalent O(1)Ca2Bi3 trigonal bipyramids. In the third O site, O(3) is bonded in a square co-planar geometry to four equivalent Bi(1) atoms.