A polyimide (PI) composite containing SiO 2 and TiO 2 hybridized nanoparticles was prepared by the sol-gel process. Polyamic acid (PAA) solution, the precursor of PI, was synthesized from 2,2¢-bis-(3,4-dicarboxyphenyl) hexofluoropropane dianhydride and bis [4-(3-aminophenoxy) phenyl sulfone in N-methyl-2-pyrrolidone. The SiO 2-TiO 2 hybrid nanoparticles were prepared by the sol-gel process in a PAA solution into which tetraethoxysilane, titanium (IV) tetrabutoxide and acetylacetone were mixed for subsequent hydrolysis and condensation reactions. After spin coating of this solution onto a glass substrate, the stepwise imidization to PI and the simultaneous gelation of the SiO 2-TiO 2 hybrid oxides were achieved at 100-300 1C. The complementing effects of reduced particle size and enhanced thermal stability of SiO 2 and TiO 2 on the resulting nanocomposite were observed. The former effect was contributed by TiO 2 and the latter by SiO 2. Uniform dispersion of 5-to 10-nm-diameter SiO 2-TiO 2 nanoparticles was obtained in the PI matrix. A 5-lm-thick film obtained from this procedure exhibited excellent optical transparency (91%, 500 nm) at 15 wt% SiO 2 for a TiO 2 content o5 wt%.