CaTi2O4 crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted CaO5 square pyramids that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, edges with three equivalent Ti(1)O6 octahedra, edges with two equivalent Ca(1)O5 square pyramids, and  a faceface with one Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 18-66°. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), two equivalent O(1), and three equivalent O(3) atoms to form distorted TiO6 octahedra that share corners with four equivalent Ti(2)O6 octahedra, corners with two equivalent Ca(1)O5 square pyramids, edges with four equivalent Ti(1)O6 octahedra, and edges with three equivalent Ca(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 48-54°. In the second Ti site, Ti(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form TiO6 octahedra that share corners with four equivalent Ti(1)O6 octahedra, corners with four equivalent Ca(1)O5 square pyramids, edges with four equivalent Ti(2)O6 octahedra, and  a faceface with one Ca(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 48-54°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ti(2), and two equivalent Ti(1) atoms to form OCaTi3 trigonal pyramids that share corners with two equivalent O(3)Ca2Ti3 square pyramids,  a cornercorner with one O(4)Ca2Ti3 trigonal bipyramid, corners with two equivalent O(1)CaTi3 trigonal pyramids, edges with three equivalent O(3)Ca2Ti3 square pyramids, and edges with two equivalent O(4)Ca2Ti3 trigonal bipyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ti(1) and two equivalent Ti(2) atoms. In the third O site, O(3) is bonded to two equivalent Ca(1) and three equivalent Ti(1) atoms to form OCa2Ti3 square pyramids that share corners with two equivalent O(4)Ca2Ti3 trigonal bipyramids, corners with two equivalent O(1)CaTi3 trigonal pyramids, edges with four equivalent O(3)Ca2Ti3 square pyramids,  an edgeedge with one O(4)Ca2Ti3 trigonal bipyramid, and edges with three equivalent O(1)CaTi3 trigonal pyramids. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and three equivalent Ti(2) atoms to form distorted OCa2Ti3 trigonal bipyramids that share corners with two equivalent O(3)Ca2Ti3 square pyramids,  a cornercorner with one O(1)CaTi3 trigonal pyramid,  an edgeedge with one O(3)Ca2Ti3 square pyramid, edges with four equivalent O(4)Ca2Ti3 trigonal bipyramids, and edges with two equivalent O(1)CaTi3 trigonal pyramids.
CaTi2O4 crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted CaO5 square pyramids that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, edges with three equivalent Ti(1)O6 octahedra, edges with two equivalent Ca(1)O5 square pyramids, and  a faceface with one Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 18-66°. The Ca(1)-O(1) bond length is 2.36 Å. Both Ca(1)-O(3) bond lengths are 2.31 Å. Both Ca(1)-O(4) bond lengths are 2.31 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), two equivalent O(1), and three equivalent O(3) atoms to form distorted TiO6 octahedra that share corners with four equivalent Ti(2)O6 octahedra, corners with two equivalent Ca(1)O5 square pyramids, edges with four equivalent Ti(1)O6 octahedra, and edges with three equivalent Ca(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 48-54°. The Ti(1)-O(2) bond length is 1.96 Å. Both Ti(1)-O(1) bond lengths are 2.06 Å. There are two shorter (2.09 Å) and one longer (2.22 Å) Ti(1)-O(3) bond length. In the second Ti site, Ti(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form TiO6 octahedra that share corners with four equivalent Ti(1)O6 octahedra, corners with four equivalent Ca(1)O5 square pyramids, edges with four equivalent Ti(2)O6 octahedra, and  a faceface with one Ca(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 48-54°. The Ti(2)-O(1) bond length is 1.99 Å. Both Ti(2)-O(2) bond lengths are 2.01 Å. There is one shorter (2.04 Å) and two longer (2.16 Å) Ti(2)-O(4) bond lengths. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ti(2), and two equivalent Ti(1) atoms to form OCaTi3 trigonal pyramids that share corners with two equivalent O(3)Ca2Ti3 square pyramids,  a cornercorner with one O(4)Ca2Ti3 trigonal bipyramid, corners with two equivalent O(1)CaTi3 trigonal pyramids, edges with three equivalent O(3)Ca2Ti3 square pyramids, and edges with two equivalent O(4)Ca2Ti3 trigonal bipyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ti(1) and two equivalent Ti(2) atoms. In the third O site, O(3) is bonded to two equivalent Ca(1) and three equivalent Ti(1) atoms to form OCa2Ti3 square pyramids that share corners with two equivalent O(4)Ca2Ti3 trigonal bipyramids, corners with two equivalent O(1)CaTi3 trigonal pyramids, edges with four equivalent O(3)Ca2Ti3 square pyramids,  an edgeedge with one O(4)Ca2Ti3 trigonal bipyramid, and edges with three equivalent O(1)CaTi3 trigonal pyramids. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and three equivalent Ti(2) atoms to form distorted OCa2Ti3 trigonal bipyramids that share corners with two equivalent O(3)Ca2Ti3 square pyramids,  a cornercorner with one O(1)CaTi3 trigonal pyramid,  an edgeedge with one O(3)Ca2Ti3 square pyramid, edges with four equivalent O(4)Ca2Ti3 trigonal bipyramids, and edges with two equivalent O(1)CaTi3 trigonal pyramids.