The drive for increasing energy efficiency and reducing greenhouse gas emissions has garnered increasing support for the use of fuel cell technology, which offers the potential for applications ranging from transport to stationary power generation. In terms of the former, polymer electrolyte (both acidic and alkaline) fuel cells are being investigated, while for the latter, solid oxide fuel cells, which represent all solid state systems operating at elevated temperature (500-1000○C), are the preferred option. In both these areas, there is a drive to develop new materials with improved properties, and the correlation between structure and properties is vital in such work. In this work the structures of hydrated La2NiO4 and phosphate doped Ba2In2O5 will be investigated in order to locate the proton site, and the location/orientation of the phosphate for the latter.