Ba0.5Sr0.5TiO3/Bi1.5Zn1.0Nb1.5O7 (BST/BZN) multilayer thin. films were prepared on Pt/Al2O3 substrates by sol-gel method. The structure, morphology, and tunable dielectric properties of BST/BZN thin. films were investigated. X-ray diffraction results showed that the structure of BST/BZN multilayer thin. films was composed of a cubic BZN pyrochlore phase and a cubic BST perovskite phase. The diffraction pattern confirmed that there was no measurable reaction occurred between the BST and BZN layers. The. field-emission scanning electron microscope (FESEM) showed that the surface of BST/BZN multilayer thin. films was crack-free and compact. The dielectric constant and loss tangent of the BST/BZN multilayer thin. films were 106 and 0.011 at 10 kHz, respectively. The dielectric tunability was 10% under dc bias. field of 355 kV/cm at 10 kHz. The medium dielectric constant, low loss tangent and tunability of the dielectric constant suggest that BST/BZN multilayer thin. films have potential application for tunable microwave device applications. (C) 2008 Elsevier B. V. All rights reserved.