Interfacial reactions of BaF2 and TiO2 were investigated in preparing BaTiO3 thin films using a fluoride precursor method. Trifluoroacetate solutions were prepared from barium acetate, titanium tetraisopropoxide (TTIP), and trifluoroacetic acid (TFA, CF3COOH) with additives such as water and acetylacetone. The solutions were deposited on platinized Si wafers by spin-coating, were pyrolysed at 400 degreesC in air and were finally heated typically at 700 degreesC in a water vapor atmosphere. The perovskite BaTiO3 phase was obtained although a small portion of BaF2 remained unreacted. Thus, the films were characterized as the mixture of BaTiO3, BaF2, and amorphous TiO2. Influence of the solution chemistry on the phase evolution and microstructure was examined in order to discuss the reaction pathway of the perovskite phase. (C) 2003 Elsevier B.V. All rights reserved.