In previous publications we reported the synthesis and characterization of silsesquioxanes derived from the hydrolytic condensation of (3-glycidoxypropyl) trimethoxysilane (GPMS) using diglycidylether of bisphenol A (DGEBA) as a solvent [1,2]. The reaction product has aliphatic epoxy groups supplied by the silsesquioxane and aromatic epoxy groups supplied by the solvent. Solutions containing 0, 25 and 50% aliphatic epoxy groups, were cured with different hardeners: methyltetrahydrophthalic anhydride (MTHPA), ethylenediamine (EDA) and benzyldimethylamine (BDMA). Silsesquioxane-modified epoxy networks showed a significant increase in the elastic modulus in the rubbery state, the abrasion resistance and the development of strain hardening in uniaxial compression tests.