The effects of thermal annealing on Pb(Zr0.3Ti0.7)O-3 ferroelectric thin film capacitors derived by chemical solution deposition with Pt electrodes were investigated. Sample-averaged structural information of the capacitors with different thermal histories was obtained from fitting the X-ray specular reflectivity using a homogeneous stratified multilayered structure model of Pt/PZT/Pt/TiOx/SiO2. Electrical measurements showed a remarkable remanent polarization reduction of up to 8.8% and an increase of the dielectric constant at low biases with increasing annealing time from 5 to 10 min. However, no evident change to the fatigue endurance was found except for the reduced initial remanent polarization. The effects of the thermal annealing on the electrical properties of the ferroelectric capacitors are discussed in correlation with the structural changes in the ferroelectric thin films. (c) 2007 The Electrochemical Society.