The effects of adding a Ba0.5Sr0.5TiO3 (BST) seeding layer of perovskite-based oxide CaCu3Ti4O12 (CCTO) thin films grown on Pt/TiN/SiO2/Si (100) substrates on crystallographic structure, surface morphology, dielectric loss, leakage current, and thermal stability were investigated. Adding a BST seeding layer to the interface between CCTO/Pt structures has remarkable influences on CCTO thin-film properties, including dielectric properties, insulating characteristics, and the temperature coefficient of capacitance (TCC), as well as thin-film grain sizes. CCTO films with a 2 nm BST seeding layer showed smaller grain sizes than those specimens of CCTO films without a BST seeding layer. The dielectric loss, leakage current density, surface roughness, and thermal stability (TCC) of CCTO films with a 2 nm BST seeding layer were improved by about 23%, 1 order of magnitude at 360 kV/cm, 38%, and 61%, respectively, compared with that of CCTO films without a BST seeding layer. The correlations of material properties, such as dielectric loss, leakage current, surface roughness, and thermal stability properties, suggest that adding a 2 nm BST seeding layer to CCTO films capacitor structure is another optimal choice for metal-insulator-metal device applications. (C) 2008 The Electrochemical Society.