BaTiO3, thin films were processed hydrothermally on Ag-coated quartz substrates at 90 degrees C by reacting films of titanium dimethoxy dineodecanoate (TDD) in aqueous solutions of Ba(OH),, Two reaction sequences were used: either the TDD was reacted directly in aqueous Ba(OW),, or the TDD was first pyrolyzed in air at temperatures ranging from 200 degrees to 500 degrees C before hydrothermal reaction. Depending on the processing conditions, the dielectric constant of the thin films ranged from 5 to 170, the dielectric constant increasing with increasing pyrolysis temperature. Thin film porosimetry data suggest that the improvement in film dielectric performance is related to decreases in thin film residual porosity after hydrothermial reaction.