Gd3OsO7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded to one O(2), two equivalent O(3), and four equivalent O(1) atoms to form distorted GdO7 pentagonal bipyramids that share corners with two equivalent Os(1)O6 octahedra, corners with three equivalent Gd(1)O7 pentagonal bipyramids, edges with two equivalent Os(1)O6 octahedra, and edges with two equivalent Gd(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 37°. In the second Gd site, Gd(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. Os(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form OsO6 octahedra that share corners with two equivalent Os(1)O6 octahedra, corners with four equivalent Gd(1)O7 pentagonal bipyramids, and edges with four equivalent Gd(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Gd(2), two equivalent Gd(1), and one Os(1) atom to form distorted OGd3Os trigonal pyramids that share corners with four equivalent O(3)Gd4 tetrahedra, corners with eight equivalent O(1)Gd3Os trigonal pyramids, edges with two equivalent O(3)Gd4 tetrahedra, and edges with two equivalent O(1)Gd3Os trigonal pyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Gd(1) and two equivalent Os(1) atoms. In the third O site, O(3) is bonded to two equivalent Gd(1) and two equivalent Gd(2) atoms to form OGd4 tetrahedra that share corners with six equivalent O(3)Gd4 tetrahedra, corners with eight equivalent O(1)Gd3Os trigonal pyramids,  an edgeedge with one O(3)Gd4 tetrahedra, and edges with four equivalent O(1)Gd3Os trigonal pyramids.
Gd3OsO7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded to one O(2), two equivalent O(3), and four equivalent O(1) atoms to form distorted GdO7 pentagonal bipyramids that share corners with two equivalent Os(1)O6 octahedra, corners with three equivalent Gd(1)O7 pentagonal bipyramids, edges with two equivalent Os(1)O6 octahedra, and edges with two equivalent Gd(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 37°. The Gd(1)-O(2) bond length is 2.54 Å. There is one shorter (2.24 Å) and one longer (2.26 Å) Gd(1)-O(3) bond length. There are two shorter (2.35 Å) and two longer (2.39 Å) Gd(1)-O(1) bond lengths. In the second Gd site, Gd(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. All Gd(2)-O(1) bond lengths are 2.67 Å. All Gd(2)-O(3) bond lengths are 2.34 Å. Os(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form OsO6 octahedra that share corners with two equivalent Os(1)O6 octahedra, corners with four equivalent Gd(1)O7 pentagonal bipyramids, and edges with four equivalent Gd(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. Both Os(1)-O(2) bond lengths are 1.97 Å. All Os(1)-O(1) bond lengths are 1.97 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Gd(2), two equivalent Gd(1), and one Os(1) atom to form distorted OGd3Os trigonal pyramids that share corners with four equivalent O(3)Gd4 tetrahedra, corners with eight equivalent O(1)Gd3Os trigonal pyramids, edges with two equivalent O(3)Gd4 tetrahedra, and edges with two equivalent O(1)Gd3Os trigonal pyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Gd(1) and two equivalent Os(1) atoms. In the third O site, O(3) is bonded to two equivalent Gd(1) and two equivalent Gd(2) atoms to form OGd4 tetrahedra that share corners with six equivalent O(3)Gd4 tetrahedra, corners with eight equivalent O(1)Gd3Os trigonal pyramids,  an edgeedge with one O(3)Gd4 tetrahedra, and edges with four equivalent O(1)Gd3Os trigonal pyramids.