We have synthesized quantum-well structured high-T-c superconductors through soft-chemical processes, where Bi-based cuprate lattices are regularly interstratified with atom, molecule, and ionic salt. In these materials, superconducting (S) and nonsuperconducting (I) layers are alternately stacked to form superlattices with atomically clear-cut interfaces between them. The intercalation technique, which means a reaction of incorporating chemical species (guest) into the pre-synthesized layered compound (host), could provides an easy route to superconducting superlattices with molecular-level layer-by-layer structural feature. The joint analysis of temperature-dependent magnetic susceptibilities and X-ray absorption spectroscopy indicated that superconducting transition temperature is predominantly governed by the electronic structure of superconductive CuO2 plane. (C) 2003 Elsevier B.V. All rights reserved.