Sol-gel is a chemical synthesis route starting from liquid precursors, the sol, which can be transformed into a gel by inorganic polymerization reactions. Finally the gel is converted to the desired oxide powder by thermal or thermooxidative decomposition. In stead of powder production, the precursors can be applied for the deposition of thin films as well. Deposition techniques that are suitable for optimized precursors include spin-coating, dip-coating and spraycoating. The deposition can be carried out on a wide variety of substrates, yielding large area, uniform films with thicknesses ranging from several hundred of nm down to a few nm. Within IMO-IMOMEC, special expertise is built for aqueous precursor systems, from which a large number of oxides is accessible. In this way, the deposition of most any complex oxide composition is possible over a wide thickness range.