Doped cerias are currently being used as oxide ion conducting electrolyte materials in solid oxide fuel cells (SOFCs). The conduction mechanism in electrolytes is dependent on the local structure. We have found very unusual local structure features in praseodymium doped ceria that cannot be accounted for in the average crystallographic model. The present proposal seeks to examine whether these local features are also present in the closely related neodymium doped ceria or are unique to the praseodymium doped system. A study of the local structure in neodymium doped ceria as a function of composition and temperature is proposed.