Three epoxy resins were examined in this study: Eporite-901 (474 g/eq), Eporite-904 (807 g/eq) and Eporite-909 (1915 g/eq), which are bisphenol-A-type epoxy resins. In this study, we used an amine terminated organically modified silicate (Ormosil) that was compatible with the diglycidyl ether of bisphenol-A epoxy to partially replace the epoxy resin at various ratios, cured by hexahydrophthalic anhydride (HHPA). The thermal and optical properties of the Ormosil-modified epoxy resins (Epoxy/Ormosil) were studied. The M n and M w of the resulting hybrids were in the range of 10668-31450 and 30617-120422, respectively, with a polydispersity index range of 2.870-3.829. The thermogravimetric analysis (TGA) results implied that Ormosil can raise the crosslink density and enhance the thermal properties. The optical properties were measured after curing and thermal aging of the polymer films with thickness around 8-10 mm. The refractive indexes of the Epoxy/Ormosil hybrids were 1.62-1.68, and the transmittances of the cured composites were above 85% in the visible wavelength.The key attributes of Epoxy/Ormosil hybrids that make them attractive materials for LEDs including their high transparency in the UV-visible region, controlled refractive index (RI), and excellent thermal resistance.