Perovskites from the series (La,Sr)(Co,Ni,Fe)O3 are promising cathode materials for solid oxide fuel cells (SOFCs) due to their high electronic conductivity and fast oxygen exchange kinetics. Thin layers of these oxides were prepared by pulsed laser deposition (PLD) and spin coating. The thickness of the films was in the range of 100 nm – 1 µm. La0.6Sr0.4CoO3 (LSC64), which served as a model material, was deposited on solid electrolyte substrates of Y2O3-stabilised zirconia (YSZ) or Gd2O3-doped ceria (GDC). Subsequently, a synthesis route for the new cathode material LaNi0.6Fe0.4O3 (LNF64) was developed based on acetates or nitrates in aqueous solution. Structure, composition and electrical properties of the thin oxide films from different preparation methods were investigated with regard to basic research issues, but also as important parameters for SOFC-cathodes. The results of this characterisation were taken into account for the optimisation of the preparation methods. First long-time studies on the stability of LSC64-nano layers during 2000 h in dry and humid atmosphere, which are of special importance for the application in the SOFC, were performed by electrochemical impedance spectroscopy.