Oxide ion conductors based on bismuth oxide based have recently been demonstrated as viable alternatives to traditional electrolytes for intermediate temperature solid oxide fuel cells. The BIMEVOX family of solid electrolytes based on substitution of V and/or Bi in Bi4V2O11-delta, exhibit some of the highest known oxide ion conductivities at low and intermediate temperature. We have previously predicted that in the Ge4+ and Sn4+ substituted BIMEVOXes, these cations adopt different coordination geometries, which leads to different solid solution limits and phase behaviour. Using reverse Monte Carlo analysis of total neutron and X-ray scattering we propose to examine differences in the cation coordination and oxide ion vacancy distribution in these BIMEVOX systems and compare these with the theoretical predictions.