A review.The sol-gel reaction of bisphenol-A type polycarbonate (PC) oligomer (PCS) having triethoxysilyl groups at both chain ends and that of PCS with tetraethoxysilane (TEOS) or tetramethoxysilane oligomer provided two types of silica films containing organic-inorganic hybrid materials; the former low silica (PCS-HM) and the latter high silica (HSPC-HM), resp.The PCS-HM film was superior to the PC film and inferior to the HSPC-HM film in terms of morphol. homogeneity, heat resistance, mech. strength, and surface hardness.The HSPC-HM films had the min. oxygen permeability at a PCS/TEOS weight ratio of 3/7.On the other hand, Si concentration-gradated hybrid materials obtained by consecutively coating HSPC-HMs having various PCS/TEOS weight ratios had large thermal shock resistance and its silica surface was stable to organic solvents.