In this work we study the influence of a hyperbranched polymer (BOLTORN (R) H20) on the thermal curing and photocuring of DGEBA. Addition of low amounts of H20 slowed down dynamic thermal curing but further addition accelerated the process. During isothermal photocuring, H20 decelerated the process at low temperatures and accelerated it at high temperatures. The temperature dependence of H20 solubility, its viscosity and the hydroxyl-induced chain-transfer reaction, are responsible for this behaviour. The addition of H20 resulted in a decrease in the glass transition temperature using both curing techniques but in a different way. (C) 2010 Elsevier B.V. All rights reserved.