Ba0.80Sr0.20TiO3/PbO-B2O3 thick films containing sol-gel derived Ba0.80Sr0.20TiO3 perovskite phase have been fabricated by using the PbO-B2O3 glass as a sintering aid. TG/DTA, XRD, SEM and an impedance analyzer were used to characterize the structure, microstructure and dielectric properties of the thick films. Compared with the conventional sintering at > 1200 degrees C, high densification of the thick films is achieved at temperature as low as 750 degrees C by the high infiltration of the PbO-B2O3 liquid phase on the particles. Only the BST phase exists in the thick films sintered at < 750 degrees C by controlling the sintering temperature and time. The formation of the small amount of the Ba2TiO4 phase in the thick film sintered at 800 degrees C results from the interdiffusion between the BST and the glass. The dielectric properties of the thick films show the dielectric relaxation various with the sintering temperature. Grain size and compositional fluctuation are two major factors affecting the broadening of ferroelectric to paraelectric transition for the BST phase in the thick films. The slight increase in dielectric loss results from the defects and vacancies generated by the interdiffusion. (c) 2005 Elsevier B.V. All rights reserved.