Sb- and Nb-doped tin oxides have been prepared by a co-precipitation method. Whilst X-ray powder diffraction and EDX mapping indicate similar dopant distributions, more detailed characterisation by variable high-temperature XRD, Sn-119 MAS NMR and Nb K-edge X-ray absorption near edge structure spectroscopy reveal clear differences in the oxide structures. This detailed structural information is used to validate the measured differences in electrical conductivity.