Na2CoO3 crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted NaO6 pentagonal pyramids that share corners with four equivalent Co(1)O4 tetrahedra, corners with two equivalent Na(2)O5 trigonal bipyramids, edges with three equivalent Na(1)O6 pentagonal pyramids, edges with two equivalent Co(1)O4 tetrahedra,  an edgeedge with one Na(2)O5 trigonal bipyramid, and faces with two equivalent Na(2)O5 trigonal bipyramids. In the second Na site, Na(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent Na(1)O6 pentagonal pyramids, corners with four equivalent Co(1)O4 tetrahedra,  an edgeedge with one Na(1)O6 pentagonal pyramid,  an edgeedge with one Co(1)O4 tetrahedra, edges with two equivalent Na(2)O5 trigonal bipyramids, and faces with two equivalent Na(1)O6 pentagonal pyramids. Co(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form CoO4 tetrahedra that share corners with four equivalent Na(1)O6 pentagonal pyramids, corners with four equivalent Na(2)O5 trigonal bipyramids, edges with two equivalent Na(1)O6 pentagonal pyramids,  an edgeedge with one Co(1)O4 tetrahedra, and  an edgeedge with one Na(2)O5 trigonal bipyramid. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one Co(1) atom. In the second O site, O(2) is bonded to two equivalent Na(1), two equivalent Na(2), and one Co(1) atom to form distorted ONa4Co square pyramids that share corners with four equivalent O(3)Na3Co2 trigonal bipyramids, edges with two equivalent O(2)Na4Co square pyramids, and edges with two equivalent O(3)Na3Co2 trigonal bipyramids. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), and two equivalent Co(1) atoms to form distorted ONa3Co2 trigonal bipyramids that share corners with four equivalent O(2)Na4Co square pyramids, edges with two equivalent O(2)Na4Co square pyramids, and edges with two equivalent O(3)Na3Co2 trigonal bipyramids.
Na2CoO3 crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted NaO6 pentagonal pyramids that share corners with four equivalent Co(1)O4 tetrahedra, corners with two equivalent Na(2)O5 trigonal bipyramids, edges with three equivalent Na(1)O6 pentagonal pyramids, edges with two equivalent Co(1)O4 tetrahedra,  an edgeedge with one Na(2)O5 trigonal bipyramid, and faces with two equivalent Na(2)O5 trigonal bipyramids. There is one shorter (2.51 Å) and one longer (2.52 Å) Na(1)-O(1) bond length. There is one shorter (2.38 Å) and one longer (2.42 Å) Na(1)-O(2) bond length. There is one shorter (2.53 Å) and one longer (2.54 Å) Na(1)-O(3) bond length. In the second Na site, Na(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent Na(1)O6 pentagonal pyramids, corners with four equivalent Co(1)O4 tetrahedra,  an edgeedge with one Na(1)O6 pentagonal pyramid,  an edgeedge with one Co(1)O4 tetrahedra, edges with two equivalent Na(2)O5 trigonal bipyramids, and faces with two equivalent Na(1)O6 pentagonal pyramids. The Na(2)-O(3) bond length is 2.32 Å. There is one shorter (2.38 Å) and one longer (2.42 Å) Na(2)-O(1) bond length. There is one shorter (2.33 Å) and one longer (2.67 Å) Na(2)-O(2) bond length. Co(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form CoO4 tetrahedra that share corners with four equivalent Na(1)O6 pentagonal pyramids, corners with four equivalent Na(2)O5 trigonal bipyramids, edges with two equivalent Na(1)O6 pentagonal pyramids,  an edgeedge with one Co(1)O4 tetrahedra, and  an edgeedge with one Na(2)O5 trigonal bipyramid. The Co(1)-O(1) bond length is 1.73 Å. The Co(1)-O(2) bond length is 1.74 Å. There is one shorter (1.86 Å) and one longer (1.94 Å) Co(1)-O(3) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one Co(1) atom. In the second O site, O(2) is bonded to two equivalent Na(1), two equivalent Na(2), and one Co(1) atom to form distorted ONa4Co square pyramids that share corners with four equivalent O(3)Na3Co2 trigonal bipyramids, edges with two equivalent O(2)Na4Co square pyramids, and edges with two equivalent O(3)Na3Co2 trigonal bipyramids. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), and two equivalent Co(1) atoms to form distorted ONa3Co2 trigonal bipyramids that share corners with four equivalent O(2)Na4Co square pyramids, edges with two equivalent O(2)Na4Co square pyramids, and edges with two equivalent O(3)Na3Co2 trigonal bipyramids.