Dielectric properties of Pt/Bi3.25La0.75Ti3O12(BLaT)/Pt ferroelectric thin film capacitors were studied as functions of frequency (40–106 Hz) and temperature (30–590 °C). BLaT thin films showed a first-order para-ferroelectric transition around 400 °C. Pt/BLaT/Pt capacitors post-annealed in Ar exhibited broadened transition with larger losses, which was interpreted in terms of increased oxygen vacancies. Via complex impedance spectroscopy study, the conduction activation energy of the space charges was determined to be ∼1.1 eV, close to that of oxygen vacancies in perovskite materials. The impedance characteristics of Pt/BLaT/Pt were compared with those of Pt/SrBi2Ta2O9(SBT)/Pt capacitors. The impact of dielectric characteristics on fatigue resistance of BLaT films was briefly discussed in comparison with SBT films. © 2004 American Institute of Physics.