We describe a facile and eco-friendly solution approach to chemically reduce graphene oxide (GO) to high-quality graphene using nontoxic inexpensive reductants. The reduction process and mechanism of a group of eco-friendly reductants were systematically studied. These reductants perform quite differently in terms of reduction rate (L-ascorbic acid [L-AA] > D-fructose> sucrose > glucose > sodium sulfite), density of small sp(2) domains (L-AA > sodium sulfite > glucose > sucrose > D-fructose), degree of reduction (L-AA > glucose > D-fructose> sodium sulfite > sucrose), and stability of the reduced GO suspension (L-AA > D-fructose> sucrose > glucose > sodium sulfite). L-AA shows the highest reducing ability, achieving the largest extent of reduction after 10 min in the presence of ammonia. Both residual oxygen functionalities and the adsorbed oxidization products of L-AA on the graphene surface are responsible for stabilizing the reduced GO suspension over several months. (C) 2014 American Institute of Chemical Engineers