In this research, a siloxane-type epoxy resin (SG copolymer), which has pendant epoxide rings on the side chain of the polysiloxane polymer backbone, was synthesized by the hydrosilylation reaction of poly(methylhydrosiloxane) with allyl glycidyl ether. The polymer structures were characterized by H-1 NMR. The SG resin was then blended with a commercial epoxy resin (diglycidyl ether of bisphenol-A, DGEBA) at various ratios, using dicyandiamide (DICY) as a curing agent. The curing behaviors were studied by DSC. It was found that the initial curing temperature (T-i) and peak curing temperature (T-p) were increased by the addition of SG copolymer to the epoxy resin. Their morphology, mechanical properties and the stability of the cured piece were investigated using SEM, DMA and TGA, respectively. The results show that the addition of SG copolymer increases the mobility of the crosslinked network, and increases the thermal stability. (C) 2000 Elsevier Science Ltd. All rights reserved.