Solid Oxide Fuel Cells (SOFCs) are electrochemical devices capable of converting and storing energy in a sustainable and efficient way. The decrease of the operating temperature could be of great help for their diffusion. The use of nanocomposites is a smooth way to design materials with many advanced functionalities that could not be reached at the same time with only a single component. Two LSGF (La_0.6Sr_0.4Ga_0.3Fe_0.7O₃) nanocomposites have been synthesized by wet impregnating manganese and iron oxides (MOx+LSGF, with M = Fe/Mn). The composites’ powders have been extensively characterized by means of XRD, XPS, N₂-asdorption, SEM, EDX, TPR, O₂-TPD and the results compared with those obtained for LSGF. The supporting perovskite stabilizes the lower oxidation states of Mn and Fe and a deep interaction between the deposited oxides and the perovskite surface is evident. Both Mn and Fe diffuse inside the perovskite during thermal treatments and this phenomenum greatly affect oxygen vacancies, mobility, and exchange capability. The catalytic activity for methane oxidation is affected by nanocomposition. Focusing on the IT-SOFCs, two symmetric cells of the type MO_x+LSGF/CGO/LSGF+MO_x have been prepared starting from the nanocomposites’ powder. The effect of the SOFCs preparation conditions (temperature, atmosphere) on the electrode and on the cell has been assessed and compared, also through in-situ high temperature XRD, simulating, on the electrodes’ powder, the same treatment necessary to prepare the cell. The use of nanocomposites powders as starting point for electrodes allows to deeply modify the electrochemical performance. A thin, Sr/Fe-rich foil forms on the surface of the electrode during SOFC thermal and deeply improves the electrochemical behaviour of the FeO_x+LSGF cathode. The electrochemical results are encouraging for future application in SOFCs, as nanocomposite has an ASR reduced by ⅓ compared to LSGF to 2.1 Ω·cm² at 620°C.