The relationship between conductivity and structure has been investigated in a new CuF2 substituted BIMEVOX, Bi2V1-xCuxO5.5-5x/2F2x, 0.10 less than or equal to x less than or equal to 0.20 (BICUVOF). The system has been characterised by X-ray powder diffraction and ac impedance spectroscopy, BICUVOF samples, in the compositional range studied, all show the tetragonal gamma -phase structure when quenched from high temperature, however, there is evidence in the conductivity data of phase transitions associated with ordering phenomena at various temperatures. A large drop in conductivity is observed on solid solution formation. These observations are consistent with a mixed anion effect analogous to the mixed ion effect seen in cation conducting systems.