Methods for forming films from aqueous solutions at ordinary temperature and pressure are advantageous because no vacuum, no high temperature and no expensive apparatus will be required and substrates even with wide areas and/or complicated shapes are available. (La,Sr)MeO3 (Me = Cr, Mn, Fe, Co) solid solutions an very important as practical materials for solid oxide fuel cells and high-temperature steam electrolyzers. (La,Sr)MeO3 solid solutions prepared by usual solid state reaction were dissolved in hydrofluoric acid and the solutions of fluorocomplexes were obtained. Boric acid was added to the solution, the fluoride ions were consumed by the formation of BF4-, and then the fluorocomplexes were hydrolyzed to (La,Sr)MeO3 solid solutions in order to increase the amount of fluoride ions. The high crystallinity of the solid solutions were confirmed by sharp and strong X-ray diffraction peaks. A number of synthesized particles of (La,Sr)MeO3 solid solutions were observed on the substrates in scanning electron microscope images. (C) 2000 Elsevier Science B.V. All rights reserved.