GdGa2 is hexagonal omega structure structured and crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Gd is bonded to twelve equivalent Ga atoms to form a mixture of edge and face-sharing GdGa12 cuboctahedra. All Gd–Ga bond lengths are 3.22 Å. Ga is bonded in a 9-coordinate geometry to six equivalent Gd and three equivalent Ga atoms. All Ga–Ga bond lengths are 2.45 Å.