Epoxy/polyhedral oligometric silsesquioxane (POSS) hybrid materials, containing 50 wt % POSS and exhibiting good homogeneity, were obtained in a two-step preparation. Monoamine-functionalized POSS was first reacted with diglycidyl ether of bisphenol A to form an epoxy POSS precursor, which was then cured. Curing agents such as 4,4'-diaminodiphenylmethane, dicyandiamide (DICY), and diethylphosphite (DEP) were used for the synthesis of the epoxy-POSS hybrid materials. The use of small-molecule curing agents, such as DICY and DEP, efficiently avoided macrophase separations and enhanced the thermal properties of the hybrid materials. (c) 2006 Wiley Periodicals, Inc.