BaCr2O4 crystallizes in the orthorhombic Pmmn space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(3) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form edge-sharing CrO6 octahedra. In the second Cr site, Cr(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form edge-sharing CrO6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ba(1), one Cr(1), and two equivalent Cr(2) atoms to form distorted OBaCr3 trigonal pyramids that share corners with four equivalent O(3)Ba2Cr3 trigonal bipyramids, corners with three equivalent O(1)BaCr3 trigonal pyramids, corners with three equivalent O(2)BaCr3 trigonal pyramids, edges with four equivalent O(3)Ba2Cr3 trigonal bipyramids, and  an edgeedge with one O(2)BaCr3 trigonal pyramid. In the second O site, O(2) is bonded to one Ba(2), one Cr(1), and two equivalent Cr(2) atoms to form OBaCr3 trigonal pyramids that share corners with four equivalent O(3)Ba2Cr3 trigonal bipyramids, corners with three equivalent O(1)BaCr3 trigonal pyramids, corners with three equivalent O(2)BaCr3 trigonal pyramids, edges with four equivalent O(3)Ba2Cr3 trigonal bipyramids, and  an edgeedge with one O(1)BaCr3 trigonal pyramid. In the third O site, O(3) is bonded to one Ba(1), one Ba(2), one Cr(2), and two equivalent Cr(1) atoms to form distorted OBa2Cr3 trigonal bipyramids that share corners with five equivalent O(3)Ba2Cr3 trigonal bipyramids, corners with two equivalent O(1)BaCr3 trigonal pyramids, corners with two equivalent O(2)BaCr3 trigonal pyramids, edges with four equivalent O(3)Ba2Cr3 trigonal bipyramids, edges with two equivalent O(1)BaCr3 trigonal pyramids, and edges with two equivalent O(2)BaCr3 trigonal pyramids.
BaCr2O4 crystallizes in the orthorhombic Pmmn space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(3) atoms. Both Ba(1)-O(1) bond lengths are 2.57 Å. All Ba(1)-O(3) bond lengths are 2.73 Å. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(3) atoms. Both Ba(2)-O(2) bond lengths are 2.55 Å. All Ba(2)-O(3) bond lengths are 2.75 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form edge-sharing CrO6 octahedra. The Cr(1)-O(1) bond length is 1.98 Å. The Cr(1)-O(2) bond length is 2.02 Å. There are two shorter (2.01 Å) and two longer (2.04 Å) Cr(1)-O(3) bond lengths. In the second Cr site, Cr(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form edge-sharing CrO6 octahedra. Both Cr(2)-O(1) bond lengths are 2.02 Å. Both Cr(2)-O(2) bond lengths are 1.98 Å. Both Cr(2)-O(3) bond lengths are 2.03 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ba(1), one Cr(1), and two equivalent Cr(2) atoms to form distorted OBaCr3 trigonal pyramids that share corners with four equivalent O(3)Ba2Cr3 trigonal bipyramids, corners with three equivalent O(1)BaCr3 trigonal pyramids, corners with three equivalent O(2)BaCr3 trigonal pyramids, edges with four equivalent O(3)Ba2Cr3 trigonal bipyramids, and  an edgeedge with one O(2)BaCr3 trigonal pyramid. In the second O site, O(2) is bonded to one Ba(2), one Cr(1), and two equivalent Cr(2) atoms to form OBaCr3 trigonal pyramids that share corners with four equivalent O(3)Ba2Cr3 trigonal bipyramids, corners with three equivalent O(1)BaCr3 trigonal pyramids, corners with three equivalent O(2)BaCr3 trigonal pyramids, edges with four equivalent O(3)Ba2Cr3 trigonal bipyramids, and  an edgeedge with one O(1)BaCr3 trigonal pyramid. In the third O site, O(3) is bonded to one Ba(1), one Ba(2), one Cr(2), and two equivalent Cr(1) atoms to form distorted OBa2Cr3 trigonal bipyramids that share corners with five equivalent O(3)Ba2Cr3 trigonal bipyramids, corners with two equivalent O(1)BaCr3 trigonal pyramids, corners with two equivalent O(2)BaCr3 trigonal pyramids, edges with four equivalent O(3)Ba2Cr3 trigonal bipyramids, edges with two equivalent O(1)BaCr3 trigonal pyramids, and edges with two equivalent O(2)BaCr3 trigonal pyramids.