CaCuO2 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(4), two equivalent O(3), and three equivalent O(1) atoms to form edge-sharing CaO6 octahedra. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to two equivalent O(2), two equivalent O(4), and three equivalent O(3) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a distorted trigonal planar geometry to one O(2) and two equivalent O(1) atoms. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to two equivalent O(2) and two equivalent O(4) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Ca(1) and two equivalent Cu(1) atoms to form OCa3Cu2 square pyramids that share corners with three equivalent O(4)Ca3Cu2 square pyramids, corners with four equivalent O(3)Ca5 square pyramids,  an edgeedge with one O(3)Ca5 square pyramid, and edges with four equivalent O(1)Ca3Cu2 square pyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Ca(2), one Cu(1), and two equivalent Cu(2) atoms. In the third O site, O(3) is bonded to two equivalent Ca(1) and three equivalent Ca(2) atoms to form distorted OCa5 square pyramids that share corners with two equivalent O(4)Ca3Cu2 square pyramids, corners with four equivalent O(1)Ca3Cu2 square pyramids,  an edgeedge with one O(1)Ca3Cu2 square pyramid, edges with three equivalent O(4)Ca3Cu2 square pyramids, and edges with four equivalent O(3)Ca5 square pyramids. In the fourth O site, O(4) is bonded to one Ca(1), two equivalent Ca(2), and two equivalent Cu(2) atoms to form distorted OCa3Cu2 square pyramids that share corners with two equivalent O(3)Ca5 square pyramids, corners with three equivalent O(1)Ca3Cu2 square pyramids, edges with two equivalent O(4)Ca3Cu2 square pyramids, and edges with three equivalent O(3)Ca5 square pyramids.
CaCuO2 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(4), two equivalent O(3), and three equivalent O(1) atoms to form edge-sharing CaO6 octahedra. The Ca(1)-O(4) bond length is 2.35 Å. There is one shorter (2.28 Å) and one longer (2.29 Å) Ca(1)-O(3) bond length. There are a spread of Ca(1)-O(1) bond distances ranging from 2.34-2.48 Å. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to two equivalent O(2), two equivalent O(4), and three equivalent O(3) atoms. There is one shorter (2.66 Å) and one longer (2.83 Å) Ca(2)-O(2) bond length. There is one shorter (2.42 Å) and one longer (2.47 Å) Ca(2)-O(4) bond length. There are a spread of Ca(2)-O(3) bond distances ranging from 2.27-2.38 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a distorted trigonal planar geometry to one O(2) and two equivalent O(1) atoms. The Cu(1)-O(2) bond length is 1.85 Å. There is one shorter (1.95 Å) and one longer (1.96 Å) Cu(1)-O(1) bond length. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to two equivalent O(2) and two equivalent O(4) atoms. There is one shorter (1.97 Å) and one longer (1.99 Å) Cu(2)-O(2) bond length. There is one shorter (1.96 Å) and one longer (1.97 Å) Cu(2)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Ca(1) and two equivalent Cu(1) atoms to form OCa3Cu2 square pyramids that share corners with three equivalent O(4)Ca3Cu2 square pyramids, corners with four equivalent O(3)Ca5 square pyramids,  an edgeedge with one O(3)Ca5 square pyramid, and edges with four equivalent O(1)Ca3Cu2 square pyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Ca(2), one Cu(1), and two equivalent Cu(2) atoms. In the third O site, O(3) is bonded to two equivalent Ca(1) and three equivalent Ca(2) atoms to form distorted OCa5 square pyramids that share corners with two equivalent O(4)Ca3Cu2 square pyramids, corners with four equivalent O(1)Ca3Cu2 square pyramids,  an edgeedge with one O(1)Ca3Cu2 square pyramid, edges with three equivalent O(4)Ca3Cu2 square pyramids, and edges with four equivalent O(3)Ca5 square pyramids. In the fourth O site, O(4) is bonded to one Ca(1), two equivalent Ca(2), and two equivalent Cu(2) atoms to form distorted OCa3Cu2 square pyramids that share corners with two equivalent O(3)Ca5 square pyramids, corners with three equivalent O(1)Ca3Cu2 square pyramids, edges with two equivalent O(4)Ca3Cu2 square pyramids, and edges with three equivalent O(3)Ca5 square pyramids.