We wish to collect powder neutron diffraction data as a function of temperature to investigate structural changes through a phase transition in the parent thermoelectric phase Cu2ZnGeSe4. DSC data indicate a phase transition occurs at ca 450 K, which NMR data suggest is associated with a change in the number of copper sites. Significant changes are observed in electrical transport properties in the temperature range 400 < T/K < 500, which appear to indicate a change from semiconducting to metallic behaviour. We wish to exploit the contrast between Cu and Zn that is afforded by neutrons to investigate the evolution of structure, including changes in cation ordering, of the room temperature ordered stannite derivative of zinc blende through the semiconductor to metal transition and the transformation to a wurtzite-related structure at higher temperatures.