Blended hybrids based on silsesquioxane cyclohexyl trisilanol [STOH; i.e., (C-C6H11)(7)Si7O9(OH)(3)]and epoxy resin 4,5-epoxyhexyl-1,2-dimethyl acid diglycidyl ester (TDE-85) were prepared with good compatibility of STOH up to 5 wt % with TDE-85. The blended hybrid resins, with various STOH additions, were cured by 4,4-di-aminodiphenylsulfone, and the curing reactions were investigated with differential scanning calorimetry. The incorporation of STCH increased the curing reaction of TDE-85 for three active hydrogens existing in the STOH molecule. The storage moduli and glass-transition temperatures of the cured hybrid resins were studied with dynamic mechanical analysis. The cured hybrids had higher storage moduli than the pure epoxy resins at lower temperatures and increased slightly even when the temperature was above the glass-transition temperature. Two peaks appearing in tan delta curves indicated the block copolymer structure and two different glass-transition temperatures of the cured hybrid resins. The thermal stability and flame retardancy of the cured hybrid resins were investigated with thermogravimetric analysis and limited oxygen index, values, respectively. The results showed that introducing silsesquioxane-OH units into epoxy resins could improve the thermal stability and flame retardancy of the resins.