A new type of polyimide/silica (PI/SiO2) hybrid composite films was prepared by blending polymer-modified colloidal silica with the semiflexible polyimide. Polyimide was solution-imidized at higher temperature than the glass transition temperature (T-g) using 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 4,4'-diaminodiphenyl ether (ODA). The morphological observation on the prepared hybrid films by scanning electron microscopy (SEM) pointed to the existence of miscible organic-inorganic phase, which resulted in improved mechanical properties compared with pure PI. The incorporation of the silica Structures in the PI matrix also increased both T-g and thermal stability of the resulting films. (c) 2006 Wiley Periodicals, Inc.