Aim of the proposal is to perform EXAFS analyses on pure CeO2 and six different samples belonging to the Ce1-x(Nd0.74Tm0.26)xO2-x/2 system (x= 0.1, 0.2, 0.3, 0.4, 0.5, 0.6), in order to understand the relationship between the ionic conductivity and the local structure. In fact, the Ce1-xRExO2-x/2 systems (RE= trivalent rare earth ion) are characterized by high ionic conductivity at low dopant amount in the 773-973 K temperature range. This property is strictly related to the structural features and to the presence of defect aggregates. Due to their outstanding ionic conductivity, these compounds are investigated for applications as electrolytes in solid oxide cells working in the intermediate temperature range (IT-SOCs), devices that allow the production and storage of energy in a more sustainable way.