A novel noncovalent functionalization approach was presented here to exfoliate and stabilize the chemical converted graphene and the low-temperature exfoliated graphene in aqueous solution by using thionine. It was found that the thionine exhibited the pi-pi stacking force with the graphene sheets, and the attachment of thionine molecules onto the graphenes surfaces could obviously improve their solubility in water. The AFM observation further verified that the graphene sheets with single-layer to double-layer were existed in the dispersions. The electronic test indicated that the modified graphene sheets possessed excellent electronic properties. (C) 2010 Elsevier Ltd. All rights reserved.