Reduced graphene oxide (RGO)-carbon nanotube (CNT) composites were successfully fabricated by microwave-assisted reduction of graphene oxide in CNT suspension using a microwave system and their morphologies, structures and electrochemical performances as negative electrode materials of lithium ion batteries were investigated. The results show that as compared with pure RGO and CNTs, RGO-CNT composites exhibit a better electrochemical activity with a maximum reversible capacity of similar to 300 mA h g(-1) after 50 galvanostatic charge-discharge cycles due to a synergistic effect of RGO and CNTs in which CNTs act as wires conductively connecting the large RGO sheets together. The RGO-CNT composites should provide a potential feasibility for the negative electrode materials of LIBs. (c) 2012 Elsevier B.V. All rights reserved.