Ho3ReO7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to one O(3), two equivalent O(2), and four equivalent O(1) atoms to form distorted HoO7 pentagonal bipyramids that share corners with two equivalent Re(1)O6 octahedra, corners with three equivalent Ho(1)O7 pentagonal bipyramids, edges with two equivalent Re(1)O6 octahedra, and edges with two equivalent Ho(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 41°. In the second Ho site, Ho(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Re(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form ReO6 octahedra that share corners with two equivalent Re(1)O6 octahedra, corners with four equivalent Ho(1)O7 pentagonal bipyramids, and edges with four equivalent Ho(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 31°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ho(2), two equivalent Ho(1), and one Re(1) atom to form distorted OHo3Re trigonal pyramids that share corners with four equivalent O(2)Ho4 tetrahedra, corners with eight equivalent O(1)Ho3Re trigonal pyramids, edges with two equivalent O(2)Ho4 tetrahedra, and edges with two equivalent O(1)Ho3Re trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Ho(1) and two equivalent Ho(2) atoms to form OHo4 tetrahedra that share corners with six equivalent O(2)Ho4 tetrahedra, corners with eight equivalent O(1)Ho3Re trigonal pyramids,  an edgeedge with one O(2)Ho4 tetrahedra, and edges with four equivalent O(1)Ho3Re trigonal pyramids. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Ho(1) and two equivalent Re(1) atoms.
Ho3ReO7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to one O(3), two equivalent O(2), and four equivalent O(1) atoms to form distorted HoO7 pentagonal bipyramids that share corners with two equivalent Re(1)O6 octahedra, corners with three equivalent Ho(1)O7 pentagonal bipyramids, edges with two equivalent Re(1)O6 octahedra, and edges with two equivalent Ho(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 41°. The Ho(1)-O(3) bond length is 2.63 Å. There is one shorter (2.22 Å) and one longer (2.24 Å) Ho(1)-O(2) bond length. There are two shorter (2.29 Å) and two longer (2.37 Å) Ho(1)-O(1) bond lengths. In the second Ho site, Ho(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Ho(2)-O(1) bond lengths are 2.63 Å. All Ho(2)-O(2) bond lengths are 2.33 Å. Re(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form ReO6 octahedra that share corners with two equivalent Re(1)O6 octahedra, corners with four equivalent Ho(1)O7 pentagonal bipyramids, and edges with four equivalent Ho(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 31°. Both Re(1)-O(3) bond lengths are 1.92 Å. All Re(1)-O(1) bond lengths are 1.99 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ho(2), two equivalent Ho(1), and one Re(1) atom to form distorted OHo3Re trigonal pyramids that share corners with four equivalent O(2)Ho4 tetrahedra, corners with eight equivalent O(1)Ho3Re trigonal pyramids, edges with two equivalent O(2)Ho4 tetrahedra, and edges with two equivalent O(1)Ho3Re trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Ho(1) and two equivalent Ho(2) atoms to form OHo4 tetrahedra that share corners with six equivalent O(2)Ho4 tetrahedra, corners with eight equivalent O(1)Ho3Re trigonal pyramids,  an edgeedge with one O(2)Ho4 tetrahedra, and edges with four equivalent O(1)Ho3Re trigonal pyramids. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Ho(1) and two equivalent Re(1) atoms.