Barium metaplumbate (BaPbO3) thin films were prepared using a chemical solution method. Films with different thicknesses, ranging from 100 nm to 1 mu m, were deposited by the spin coating technique. After drying at 300 degrees C and firing between 600-700 degrees C in air, a room-temperature resistivity about 1 m Omega-cm was obtained, which is comparable to that of ceramic bulk. The chemical reaction sequence during heating was investigated using XRD and thermal analysis. It was found that several reactions were involved in a temperature range from 200 degrees C to 600 degrees C. The crystallized films tended to be decomposed by subsequent deposition, which resulted in the loss of conductivity of the films. However, the conductivity could be recovered by firing at higher temperatures. In addition, a thickness threshold about 1200 Angstrom was observed below which the resistivity of the films increased rapidly. This phenomenon is discussed in this study.