New dendritic modifiers have been synthesized by amidation of hyperbranched poly(ethylenimine)(PEIs) with 10-undecenoic acid to obtain hyperbranched polymers (HBPs) with different degree of modification. These HBPs have been used as toughness modifiers in a proportion of 10 and 20% in reference to the epoxy resin in diglycidyl ether of bisphenol A (DGEBA)/methyltetrahydrophthalic anhydride (MTHPA) formulations. The curing process has been studied by dynamic scanning calorimetry and by rheometry, which allow the kinetic constants and the gel and vitrification times to be evaluated. The materials obtained have been thermally characterized and their mechanical properties have been evaluated. An increase in impact resistance has been achieved and the T-g of all thermosets prepared was higher than 100 degrees C in spite of the flexible structure of the PEI modifiers. (C) 2015 Elsevier B.V. All rights reserved.