Electrochemically reduced graphene oxide modified glassy carbon electrodes (ERGC) were obtained under various reducing conditions to control the content of oxygen-functional groups (OxFG). By utilizing Fe(CN)(6)(3-)/Fe(CN)(6)(4-). AA and DA as redox probes cyclic voltammogram (CV) and differential pulse voltammogram (DPV) results indicated that for various substances the effect of OxFG was distinct and different types of OxFG (C=O, C-O-C, -OH, -COOH, etc.) played entirely different roles for one substance which were reflected in peak potential shift and peak current change. Finally, the optimum reducing conditions of fabricating ERGC for the detection of AA and DA separately and simultaneously were explored and satisfactory results were obtained. (C) 2011 Elsevier B.V. All rights reserved.