Antimony substituted lanthanum niobium oxide is a recently developed proton conductor with potential use in fuel cells, gas sensors and steam electrolysers Our preliminary work has revealed that not only does antimony substitution enhance conductivity, it also stabilizes the highly conducting scheelite phase to room temperature in contrast to the unsubstituted system which exhibits the more poorly conducting furgusonite structure at ambient temperatures. Other work suggests that the oxide ion separation distance plays a major role in determining the enthalpy of proton diffusion in these systems. A study of the correlation between electrical behaviour and oxide ion separation distance and distortion in the metal coordination environment using neutron diffraction is proposed. Details of the individual contributions of antimony and niobium will be studied using a total scattering approach.