BaBiO3 crystallizes in the triclinic P1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms. In the second Ba site, Ba(2) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(6), two equivalent O(1), and two equivalent O(5) atoms. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 3-coordinate geometry to one O(3), one O(4), and one O(5) atom. In the second Bi site, Bi(2) is bonded in an L-shaped geometry to one O(1), one O(2), and one O(6) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Ba(1), two equivalent Ba(2), and one Bi(2) atom to form OBa3Bi tetrahedra that share corners with two equivalent O(1)Ba3Bi tetrahedra, corners with three equivalent O(5)Ba3BiO trigonal bipyramids,  a cornercorner with one O(4)Ba2BiO trigonal pyramid,  an edgeedge with one O(5)Ba3BiO trigonal bipyramid, and  an edgeedge with one O(4)Ba2BiO trigonal pyramid. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Bi(2), and one O(5) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ba(1), one Bi(1), and one O(4) atom. In the fourth O site, O(4) is bonded to one Ba(1), one Ba(2), one Bi(1), and one O(3) atom to form OBa2BiO trigonal pyramids that share  a cornercorner with one O(1)Ba3Bi tetrahedra, corners with two equivalent O(5)Ba3BiO trigonal bipyramids,  an edgeedge with one O(1)Ba3Bi tetrahedra, and  an edgeedge with one O(5)Ba3BiO trigonal bipyramid. In the fifth O site, O(5) is bonded to one Ba(1), two equivalent Ba(2), one Bi(1), and one O(2) atom to form distorted OBa3BiO trigonal bipyramids that share corners with three equivalent O(1)Ba3Bi tetrahedra, corners with two equivalent O(5)Ba3BiO trigonal bipyramids, corners with two equivalent O(4)Ba2BiO trigonal pyramids,  an edgeedge with one O(1)Ba3Bi tetrahedra, and  an edgeedge with one O(4)Ba2BiO trigonal pyramid. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(2), and one Bi(2) atom.
BaBiO3 crystallizes in the triclinic P1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms. The Ba(1)-O(1) bond length is 2.60 Å. The Ba(1)-O(3) bond length is 2.93 Å. The Ba(1)-O(4) bond length is 2.90 Å. The Ba(1)-O(5) bond length is 2.68 Å. The Ba(1)-O(6) bond length is 2.70 Å. There is one shorter (2.72 Å) and one longer (2.75 Å) Ba(1)-O(2) bond length. In the second Ba site, Ba(2) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(6), two equivalent O(1), and two equivalent O(5) atoms. The Ba(2)-O(2) bond length is 2.78 Å. The Ba(2)-O(4) bond length is 2.66 Å. The Ba(2)-O(6) bond length is 2.80 Å. There is one shorter (2.65 Å) and one longer (2.69 Å) Ba(2)-O(1) bond length. There is one shorter (2.72 Å) and one longer (2.92 Å) Ba(2)-O(5) bond length. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 3-coordinate geometry to one O(3), one O(4), and one O(5) atom. The Bi(1)-O(3) bond length is 2.24 Å. The Bi(1)-O(4) bond length is 2.27 Å. The Bi(1)-O(5) bond length is 2.66 Å. In the second Bi site, Bi(2) is bonded in an L-shaped geometry to one O(1), one O(2), and one O(6) atom. The Bi(2)-O(1) bond length is 2.10 Å. The Bi(2)-O(2) bond length is 2.89 Å. The Bi(2)-O(6) bond length is 2.09 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Ba(1), two equivalent Ba(2), and one Bi(2) atom to form OBa3Bi tetrahedra that share corners with two equivalent O(1)Ba3Bi tetrahedra, corners with three equivalent O(5)Ba3BiO trigonal bipyramids,  a cornercorner with one O(4)Ba2BiO trigonal pyramid,  an edgeedge with one O(5)Ba3BiO trigonal bipyramid, and  an edgeedge with one O(4)Ba2BiO trigonal pyramid. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Bi(2), and one O(5) atom. The O(2)-O(5) bond length is 1.48 Å. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ba(1), one Bi(1), and one O(4) atom. The O(3)-O(4) bond length is 1.48 Å. In the fourth O site, O(4) is bonded to one Ba(1), one Ba(2), one Bi(1), and one O(3) atom to form OBa2BiO trigonal pyramids that share  a cornercorner with one O(1)Ba3Bi tetrahedra, corners with two equivalent O(5)Ba3BiO trigonal bipyramids,  an edgeedge with one O(1)Ba3Bi tetrahedra, and  an edgeedge with one O(5)Ba3BiO trigonal bipyramid. In the fifth O site, O(5) is bonded to one Ba(1), two equivalent Ba(2), one Bi(1), and one O(2) atom to form distorted OBa3BiO trigonal bipyramids that share corners with three equivalent O(1)Ba3Bi tetrahedra, corners with two equivalent O(5)Ba3BiO trigonal bipyramids, corners with two equivalent O(4)Ba2BiO trigonal pyramids,  an edgeedge with one O(1)Ba3Bi tetrahedra, and  an edgeedge with one O(4)Ba2BiO trigonal pyramid. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(2), and one Bi(2) atom.