The use of commercially available hyperbranched poly(ethyleneimine)s (Hbpei, LupasolTM, BASF) as curing agent of DGEBA has been studied. HBpei can react with epoxy monomers by an epoxy-amine condensation mechanism and get incorporated into the network structure of the thermoset. The resulting materials have been compared with those obtained using diethylenetriamine (DETA) as curing agent. The curing kinetics have been studied with DSC and rheology. The thermal–mechanical properties have been determined with DMA and DSC. The thermal stability has been assessed with TGA. The curing kinetics and the different transformations that take place during curing of both formulations have been summarized in a TTT diagram. Because of the low mobility of HBpei, curing kinetics is slower than the formulations with DETA. Both HBpei and DETA produce homogeneous materials with similar Tg and thermal stability, but HBpei materials are more densely crosslinked than DETA because of the preexisting internal crosslinks of HBpei.