In the field of thermoelectricity, Co-free filled skutterudites represent an interesting class of materials thanks to their ability to host different amount of filler ions, which tune their conduction regime and transport properties. Aim of this proposal is to perform EXAFS analyses on three samples belonging to the double filled skutterudite system (La,Sm)y(FexNi1-x)4Sb12 at the La and the Sm K-edge to obtain information about the local variations induced by the introduction of two different fillers. Data on a sample of the single filled skutterudite Smy(FexNi1-x)4Sb12 will be also collected at the Sm and Sb K-edge to have a term of comparison. Moreover, the oxidation state of Fe and Ni will be investigated by exploring the XANES region of the spectrum. The so gained information can be of help in the comprehension of the mechanism of thermal conductivity suppression operated by filling in filled skutterudites.