As an origin of degradation of remnant polarization in Pt/BaTiO33/Pt capacitor structure, an interfacial layer formed at the interface of BaTiO (film and a Pt bottom electrode is considered. BaTiO)(3) (films were deposited on two types of bottom electrodes (La)(Sr)(CoO)(0.5)(0.5)(3) (and Pt) by the radio frequency magnetron sputtering method and both capacitors showed a microstructural similarity with strong preferred orientations. However, a Pt/BaTiO)(/La)(Sr)(CoO)(3)(0.5)(0.5)(3) (capacitor exhibited a saturated hysteresis loop with the remnant polarization (2P)() of 6 mC/cm2, and for the Pt/BaTiO)(/Pt structure, the polarization-voltage curve revealed a linear dielectric characteristic. From a cross-sectional high-resolution transmission electron microscope analysis of the Pt/BaTiO)(/Pt capacitor showing the linear dielectric property, an interfacial layer with an amorphous structure as well as a multidomain structure in the interior of the BaTiO)(r)(3)(3)(3) film were observed. It is concluded that the interfacial layer might help degradation of polarization and its origin can be classified as being extrinsic. 2005 American Institute of Physics.