Solid oxide fuel cells (SOFCs) have been rapidly developed for efficient power generation applications. One of the major activities at Imperial College concerns the development of intermediate-temperature SOFCs, and the exploitation of cost-effective fabrication processes to address the crucial technical problems which have hindered the commercialisation of SOFCs. These involve the strategic investigation on the development of planar supported thin film electrolyte PEN (positive electrode/electrolyte/negative electrode) structure [La(Sr)MnO3/ Zr(Y)O2-x/Ni-ZrO2], and SOFCs based on La0.9Sr0.1Ga0.8Mg0.2O3-x (LSGM) electrolytes for intermediate temperature operation (700-800 degrees C), and to exploit the electrostatic assisted vapour deposition (EAVD) and the flame assisted vapour deposition (FAVD) as novel, simple and cost-effective methods to manufacture SOFC components and multilayer PEN structure on large area substrates in an open atmosphere, in one production step. In addition, efforts have been directed towards developing cathode/electrolyte systems to improve the conductivities in planar SOFCs. Systems such as La0.82Sr0.18MnO3/(Y2O3)(0.15)(CeO2)(0.85)/YSZ, La0.8S0.2CoO3/(Y2O3)(0.15)(CeO2)(0.85)/YSZ, and La0.8Sr0.2CoO3/Ce0.8Gd0.2O1.9/YSZ have been investigated and compared with La0.82Sr0.18MnO3/YSZ where YSZ is 8 mol% Y2O3 in ZrO2. The process, structure and properties of the cell components and cathodes have been examined using SEM, XRD and AC-impedance spectroscopy. The results from these new systems indicate a superior performance in overall conductivity to the conventional La0.82Sr0.18MnO3/YSZ system.