The structure of Ga-doped spinel oxides with the general formula, Li1.02Mn2-xGaxO4, has been studied by neutron and X-ray powder diffraction. Rietveld refinement of the neutron data confirms that the Ga3+ ions selectively occupy the octahedral (16d) sites of the lattice. The absence of gallium ions from the tetrahedral (8a) or the additional octahedral (16c) is thought to be an important factor in the material's increased performance as a cathode in a rechargeable lithium ion battery.