Ho2Ge2O7 crystallizes in the cubic Fd-3m space group. Ho(1) is bonded to two equivalent O(1) and six equivalent O(2) atoms to form distorted HoO8 hexagonal bipyramids that share edges with six equivalent Ho(1)O8 hexagonal bipyramids and edges with six equivalent Ge(1)O6 octahedra. Ge(1) is bonded to six equivalent O(2) atoms to form GeO6 octahedra that share corners with six equivalent Ge(1)O6 octahedra and edges with six equivalent Ho(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 47°. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ho(1) atoms to form OHo4 tetrahedra that share corners with four equivalent O(1)Ho4 tetrahedra, corners with twelve equivalent O(2)Ho2Ge2 tetrahedra, and edges with six equivalent O(2)Ho2Ge2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Ho(1) and two equivalent Ge(1) atoms to form distorted OHo2Ge2 tetrahedra that share corners with two equivalent O(1)Ho4 tetrahedra, corners with twelve equivalent O(2)Ho2Ge2 tetrahedra,  an edgeedge with one O(1)Ho4 tetrahedra, and edges with four equivalent O(2)Ho2Ge2 tetrahedra.
Ho2Ge2O7 crystallizes in the cubic Fd-3m space group. Ho(1) is bonded to two equivalent O(1) and six equivalent O(2) atoms to form distorted HoO8 hexagonal bipyramids that share edges with six equivalent Ho(1)O8 hexagonal bipyramids and edges with six equivalent Ge(1)O6 octahedra. Both Ho(1)-O(1) bond lengths are 2.14 Å. All Ho(1)-O(2) bond lengths are 2.44 Å. Ge(1) is bonded to six equivalent O(2) atoms to form GeO6 octahedra that share corners with six equivalent Ge(1)O6 octahedra and edges with six equivalent Ho(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 47°. All Ge(1)-O(2) bond lengths are 1.91 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ho(1) atoms to form OHo4 tetrahedra that share corners with four equivalent O(1)Ho4 tetrahedra, corners with twelve equivalent O(2)Ho2Ge2 tetrahedra, and edges with six equivalent O(2)Ho2Ge2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Ho(1) and two equivalent Ge(1) atoms to form distorted OHo2Ge2 tetrahedra that share corners with two equivalent O(1)Ho4 tetrahedra, corners with twelve equivalent O(2)Ho2Ge2 tetrahedra,  an edgeedge with one O(1)Ho4 tetrahedra, and edges with four equivalent O(2)Ho2Ge2 tetrahedra.