Polyimide-silica (PI-SiO2) hybrids with a nanostructure was obtained using the nonaqueous sol-gel process by polycondensation of phenyltriethoxysilane in a polyamic acid solution. Self-catalyzed hydrolysis of phenyl-substituted akoxysilane and modification on the polyimide structure are applied and result in highly compatible PI-SiO2 hybrids. Transparent PI-SiO2, with a high silica content of about 45% was thus obtained. The prepared PI-SiO2, films were characterized by infrared spectrometry, Si-29-NMR, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. These characterizations showed the silica influence on the properties of the hybrid. The thermal expansion coefficient of the PI-SiO2, and the temperature correlation were also established for probing the potential for application. (C) 2000 John Wiley & Sons, Inc.