Through hard X-ray photoelectron spectroscopy (HAXPES), we find further evidence to support this description of the defect chemistry of ZnSb 2 O 6 . At high photon energies (approaching 6 keV), we can exploit the greater photoionisation cross-section of Sb 5s states, which from the density of states calculation we expect make up the conduction band minimum, allowing us to observe any filled conduction band states. Figure shows the HAXPES valence band spectra for undoped and Gadoped ZnSb 2 O 6 and an expanded view of the conduction band states in the inset. In the undoped sample, there is no photoemission at a binding energy of 0 eV, while the doped sample shows conduction band emission with a typical Fermi-Dirac-like distribution. This is strong evidence of degenerate filling of the conduction band upon Ga-doping, supporting the prediction of metallic-like conductivity from our defect calculations.