Organic/inorganic hybrids with 1 to 7% silica contents were synthesized from bisphenol-A and epichlorohydrin by utilizing gamma-thiopropyl triethoxy silane (KH580). The reactive coupling agent KH580 was introduced to epoxy resin to obtain high adhesive strength material for engineering industry. It was hypothesized that the multiple reactive functional silanol group Si-OH of KH580 after hydrolyzing reacted with epoxy resin to increase the shear strength and toughness of epoxy resin. IR spectra indicated that bonded stationary phase was formed. Shear strength of epoxy resin-based composite increased and then decreased after SiO2 content reached 5 wt %; the optimal value was 24.78 MPa. SEM analysis showed that toughness Of SiO2/epoxy resin-based composite also increased and then decreased when the content Of SiO2 is more than 5 wt %. (C) 2009 Wiley Periodicals, Inc. J AppI Polym Sci 114: 2388-2394, 2009