NaCo2O3 crystallizes in the orthorhombic Cmc2_1 space group. Na(1) is bonded to two equivalent O(1) and three equivalent O(2) atoms to form distorted NaO5 trigonal bipyramids that share corners with eight equivalent Co(1)O4 tetrahedra, corners with two equivalent Na(1)O5 trigonal bipyramids, edges with two equivalent Co(1)O4 tetrahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. Co(1) is bonded to one O(2) and three equivalent O(1) atoms to form CoO4 tetrahedra that share corners with seven equivalent Co(1)O4 tetrahedra, corners with four equivalent Na(1)O5 trigonal bipyramids, and  an edgeedge with one Na(1)O5 trigonal bipyramid. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(1) and three equivalent Co(1) atoms to form ONaCo3 tetrahedra that share corners with seven equivalent O(1)NaCo3 tetrahedra, corners with four equivalent O(2)Na3Co2 trigonal bipyramids, and  an edgeedge with one O(2)Na3Co2 trigonal bipyramid. In the second O site, O(2) is bonded to three equivalent Na(1) and two equivalent Co(1) atoms to form distorted ONa3Co2 trigonal bipyramids that share corners with eight equivalent O(1)NaCo3 tetrahedra, corners with two equivalent O(2)Na3Co2 trigonal bipyramids, edges with two equivalent O(1)NaCo3 tetrahedra, and edges with two equivalent O(2)Na3Co2 trigonal bipyramids.
NaCo2O3 crystallizes in the orthorhombic Cmc2_1 space group. Na(1) is bonded to two equivalent O(1) and three equivalent O(2) atoms to form distorted NaO5 trigonal bipyramids that share corners with eight equivalent Co(1)O4 tetrahedra, corners with two equivalent Na(1)O5 trigonal bipyramids, edges with two equivalent Co(1)O4 tetrahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. Both Na(1)-O(1) bond lengths are 2.33 Å. There are a spread of Na(1)-O(2) bond distances ranging from 2.33-2.73 Å. Co(1) is bonded to one O(2) and three equivalent O(1) atoms to form CoO4 tetrahedra that share corners with seven equivalent Co(1)O4 tetrahedra, corners with four equivalent Na(1)O5 trigonal bipyramids, and  an edgeedge with one Na(1)O5 trigonal bipyramid. The Co(1)-O(2) bond length is 1.87 Å. There are two shorter (1.93 Å) and one longer (1.99 Å) Co(1)-O(1) bond length. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(1) and three equivalent Co(1) atoms to form ONaCo3 tetrahedra that share corners with seven equivalent O(1)NaCo3 tetrahedra, corners with four equivalent O(2)Na3Co2 trigonal bipyramids, and  an edgeedge with one O(2)Na3Co2 trigonal bipyramid. In the second O site, O(2) is bonded to three equivalent Na(1) and two equivalent Co(1) atoms to form distorted ONa3Co2 trigonal bipyramids that share corners with eight equivalent O(1)NaCo3 tetrahedra, corners with two equivalent O(2)Na3Co2 trigonal bipyramids, edges with two equivalent O(1)NaCo3 tetrahedra, and edges with two equivalent O(2)Na3Co2 trigonal bipyramids.