TransparentNonlinearOptical(NLO) inorganic/organic(polyimide /silica) hybrid composites with covalent links between the inorganic and the organic networks were prepared by the sol-gel method. The silica content in the hybrid filmswas varied from0 to 22.5/wt%. The prepared PI hybridswere characterized byIR,UV-Vis, thermogravimetric analysis(TGA),X-raydiffraction(XRD), scanning electron microscopy(SEM) and Transmission Electron Microscope(TEM).They exhibit fair good optical transparency.The SiO2phase iswell dispersed in the polymermatrix.DSC and TGAresults showthat these hybridmaterials have excellent thermal stability. The polymer solutions could be spin coated on the indium-tin-oxide(ITO) glass to formoptical quality thin films. The electro-optic coefficients(ï§33) at thewavelength of 832 nmfor polymer thin films poledwere in the range of 20-30pm/V.