A facile way to prepare graphene-supported Ru catalysts was developed here. For the first time, functionalized graphene obtained from thermal exfoliation of graphite oxide at low temperature (200 degrees C) under air atmosphere was used to support Ru nanoparticles (2.3 nm) with the simple method of incipient wetness impregnation. Heat treating at 700 degrees C in N-2 flow did not change the mean size but made Ru nanoparticles electron rich. The electronic effect had a great influence on the activities of benzene and p-chloronitrobenzene hydrogenation but little influence on the activity of cinnamaldehyde hydrogenation and its selectivity of C=O bond. A geometric effect benefited from the distinctive preparation method was supposed to be another factor accounting for these catalytic phenomena. Comparing with CNTs-supported Ru catalysts obtained from a similar method, we can see clearly that graphene with the two-dimensional flexible graphitic surface could modulate the electronic and geometric structures of Ru catalysts in an unusual way. Additionally, this work provides the possibility of producing graphene-based precious metal catalysts on a large scale. (C) 2015 Elsevier Inc. All rights reserved.