A series of epoxy-bridged polyorganosiloxanes have been synthesized by reacting multifunctional aminoalkoxysilanes with diglycidyl ether of bisphenol A (DGEBA) epoxy resin. The reactions of trifunctional 3-aminopropyltriethoxysilane (APTES), difunctional 3-aminopropylmethyldiethoxysilane (APMDS), and monofunctional 3-aminopropyldimethylethoxysilane (APDES) with DGEBA epoxy have been monitored and characterized by FTIR, H-1 NMR, and Si-29 NMR spectra in this study. The synthesized epoxy-bridged polyorganosiloxanes precursors, with different terminated alkoxysilane groups, are thermally cured with or without the addition of curing catalysts. Organometallic dibutyltindilaurate, and alkaline tetrabutylammonium hydroxide have been used as curing catalysts to investigate the thermal curing behaviors and cured properties of epoxy-bridged polyorganosiloxanes precursors. The maximum exothermal curing temperatures of epoxy-bridged polyorganosiloxanes precursors are found to appear around the same region of 120 degrees C in DSC analysis. The addition of catalysts to the epoxy/APTES precursor shows significant influence on the cured structure; however, the catalysts exhibit less influence on the cured structure of epoxy-APMDS precursor and epoxy/APDES precursor. Curing catalysts also show significant enhancement in increasing the thermal decomposition temperature (T(d50)s) of cured network of trifunctional epoxy-bridged polyorganosiloxane (epoxy/ APTES). High T(d50)s of 518.8 and 613.6 in the cured hybrids of epoxy/APTES and epoxy/APMDS precursors are also observed, respectively. When trialkoxysilane-terminated epoxy-bridged polyorganosiloxanes precursor are cured, with or without the addition of catalyst, no obvious T-g transition can be found in the TMA analysis Of Cured network. The cured network of trialkoxysilane-terminated epoxy-bridged polyorganosiloxanes also exhibits the lowest coefficient of thermal expansion (CTE) among the three kinds of trialkoxysilane-terminated epoxy-bridged polyorganosiloxanes investigated. The organic-inorganic hybrid, from epoxy-bridged polyorganosiloxanes after the thermal curing process, shows better thermal stability than the cured resin network of pure epoxy-diaminopropane. (c) 2006 Wiley Periodicals, Inc.