Graphene, whose structure consists of a single layer of sp(2)-hybridized carbon atoms, provides an excellent platform for designing composite nanomaterials. In this study, we have demonstrated a facile process to synthesize graphene-multiwalled carbon nanotube (MWCNT) composite. The graphene-MWCNT composite material is endowed with a large electrochemical surface area and fast electron transfer properties in Fe(CN)(6)(3-/4-) redox species. A graphene-MWCNT composite modified electrode exhibits good performance in terms of the electrocatalytic reduction of H2O2; a sensor constructed from such an electrode shows a good linear dependence on H2O2 concentration in the range of 2 x 10(-5) to 2.1 x 10(-3) mol L-1. The detection limit is estimated to be 9.4 x 10(-6) mol L-1. This study provides a new kind of composite modified electrode for electrochemical sensors. (C) 2011 Elsevier Ltd. All rights reserved.