Pt/(Ba0.7Sr0.3)TiO3 (BST)/YBa2Cu3O7-x capacitors were prepared and investigated for the dead-layer (DL) thickness (td) and the DL dielectric constant (εd). Based on the series capacitor model, the td/εd ratio of 0.066 nm and the bulk BST ferroelectric-layer dielectric constant of 1370 were obtained through the measurements of the capacitance–voltage characteristics. The td×εd value of 120 nm was obtained through the measurements of the current–voltage characteristics. Combining these data, the DL thickness and the DL dielectric constant are respectively estimated to be 2.8 nm and 42.6. © 2004 American Institute of Physics.