CuGaO2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Cu1+ is bonded in a linear geometry to two equivalent O2- atoms. Both Cu–O bond lengths are 1.87 Å. Ga3+ is bonded to six equivalent O2- atoms to form edge-sharing GaO6 octahedra. All Ga–O bond lengths are 2.02 Å. O2- is bonded to one Cu1+ and three equivalent Ga3+ atoms to form a mixture of distorted edge and corner-sharing OGa3Cu tetrahedra.