Ferroelectric BaTiO3 thin film capacitors were fabricated using different designs. Silicon wafers with an oxide layer were used as the substrates. Conductive metallic oxide of RuO2 was reactively sputtered on SiO2/Si as a bottom electrode. The BaTiO3 thin films with a thickness in the range of 150–300nm were deposited by RF magnetron sputtering. Different capacitor structures, including single layer amorphous, single layer polycrys-talline, and bi-layer amorphous on polycrystalline, were investigated in this study. The clear interface between BaTiO3 and RuO2 as demonstrated by cross-sectional scanning electron microscopy implies little interdiffusion. The DC conducticity of a film with a thickness of around 200nm was as low as 1×10−13OHgr-cm at 4V. The dielectric constant of the composite structure was controlled in a range from 30 to 130. Breakdown voltage varied from 5×105V/cm to 1×106V/cm.