Tunable (Pb0.5Ba0.5)(Zr1-xTix)O-3 (PBZT) films were grown on Pt/Ti/SiO2/Si substrates using chemical solution deposition method. PBZT films contained bimodal distribution of grains and pores. The size of large grains, the amount of small grains, and the porosity all increased with the content of titanium oxide. The microstructural characteristics of PBZT films influenced dielectric properties. Increasing the content of TiO2 in PBZT films increased dielectric constant, tunability, and figure of merit (FOM), while it kept loss tangent relatively unchanged. The composition (x=0.2) locating near the paraelectric-fierroelectric boundary exhibited optimal dielectric tunability and FOM. The tunability and FOM were improved remarkably from 12% and 6 to 34% and 26, respectively, when 20% of titanium oxide was added to PBZ films. (c) 2006 Elsevier B.V. All rights reserved.