CaTiO2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(3), and two equivalent O(4) atoms. In the second Ca site, Ca(2) is bonded in a 3-coordinate geometry to one O(3) and two equivalent O(2) atoms. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(1) and three equivalent O(3) atoms to form TiO5 square pyramids that share corners with two equivalent Ti(2)O6 octahedra and edges with four equivalent Ti(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 49°. 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 two equivalent Ti(1)O5 square pyramids and edges with four equivalent Ti(2)O6 octahedra. 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 distorted OCaTi3 trigonal pyramids that share corners with two equivalent O(3)Ca3Ti3 octahedra,  a cornercorner with one O(4)Ca2Ti3 trigonal bipyramid, corners with two equivalent O(1)CaTi3 trigonal pyramids, edges with three equivalent O(3)Ca3Ti3 octahedra, and edges with two equivalent O(4)Ca2Ti3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 19°. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca(2) and two equivalent Ti(2) atoms. In the third O site, O(3) is bonded to one Ca(2), two equivalent Ca(1), and three equivalent Ti(1) atoms to form OCa3Ti3 octahedra 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)Ca3Ti3 octahedra,  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)Ca3Ti3 octahedra,  a cornercorner with one O(1)CaTi3 trigonal pyramid,  an edgeedge with one O(3)Ca3Ti3 octahedra, edges with four equivalent O(4)Ca2Ti3 trigonal bipyramids, and edges with two equivalent O(1)CaTi3 trigonal pyramids. The corner-sharing octahedral tilt angles are 33°.
CaTiO2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(3), and two equivalent O(4) atoms. The Ca(1)-O(1) bond length is 2.56 Å. Both Ca(1)-O(3) bond lengths are 2.41 Å. Both Ca(1)-O(4) bond lengths are 2.34 Å. In the second Ca site, Ca(2) is bonded in a 3-coordinate geometry to one O(3) and two equivalent O(2) atoms. The Ca(2)-O(3) bond length is 2.48 Å. Both Ca(2)-O(2) bond lengths are 2.29 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(1) and three equivalent O(3) atoms to form TiO5 square pyramids that share corners with two equivalent Ti(2)O6 octahedra and edges with four equivalent Ti(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 49°. Both Ti(1)-O(1) bond lengths are 2.05 Å. There is one shorter (2.09 Å) and two longer (2.17 Å) Ti(1)-O(3) bond lengths. 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 two equivalent Ti(1)O5 square pyramids and edges with four equivalent Ti(2)O6 octahedra. The Ti(2)-O(1) bond length is 1.95 Å. Both Ti(2)-O(2) bond lengths are 2.06 Å. There is one shorter (2.00 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 distorted OCaTi3 trigonal pyramids that share corners with two equivalent O(3)Ca3Ti3 octahedra,  a cornercorner with one O(4)Ca2Ti3 trigonal bipyramid, corners with two equivalent O(1)CaTi3 trigonal pyramids, edges with three equivalent O(3)Ca3Ti3 octahedra, and edges with two equivalent O(4)Ca2Ti3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 19°. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca(2) and two equivalent Ti(2) atoms. In the third O site, O(3) is bonded to one Ca(2), two equivalent Ca(1), and three equivalent Ti(1) atoms to form OCa3Ti3 octahedra 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)Ca3Ti3 octahedra,  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)Ca3Ti3 octahedra,  a cornercorner with one O(1)CaTi3 trigonal pyramid,  an edgeedge with one O(3)Ca3Ti3 octahedra, edges with four equivalent O(4)Ca2Ti3 trigonal bipyramids, and edges with two equivalent O(1)CaTi3 trigonal pyramids. The corner-sharing octahedral tilt angles are 33°.