Thin films of BaCe0.8Gd0.2O3 have been successfully prepared on both dense and porous substrates using a modified Pechini process. To increase the extent of chelation, ethylene diamine tetraacetic acid (EDTA) has been used to replace citric acid in the Pechini process. Results indicate that the most important processing parameter is the molar ratio of complexation/polymerization agent (EDTA) to metal ions (C ratio). Films derived from sets with C ratio smaller than 1 are usually cracked, while those derived from sols with C ratio greater than 2.5 are porous. Crack-free and uniform films are obtained from the sols with C ratios between 1.5 and 2.5. Thin-film membranes of barium cerate electrolytes have also been deposited on porous substrates by modifying the surface of the porous substrate with an intermediate polymer film derived from EDTA and ethylene glycol.