The aim of this work is to determine the oxygen mobility in fast ion conducting oxides using quasi elastic neutron scattering in combination with molecular dynamics studies. Previous work has indicated that broadening of the QENS signal occurs on heating of CeNbO4. Due to the nature of the phase evolution in this material the interpretation proved challenging. In this work we intend to prove the use of the technique in well understood materials: yttria stabilised zirconia and delta-Bi2O3. Measurements will be made as a function of temperature and the data correlated with ionic diffusion. As a result of this work we will be able to extend this technique to a wider range of materials, including those that cannot be characterised by other conventional techniques.