Polypyrrole-grafted nitrogen-doped graphene (PPY-g-NGE) was successfully synthesized by simultaneous modification of graphene through nitrogen doping and polymeric grafting, and used for the detection of paraquat (PQ). The chemical structure, morphology and interaction of the obtained PPY-g-NGE were verified by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The PPY-g-NGE modified glassy carbon electrode (GCE) was fabricated to investigate its electrochemical behavior and sensitive detection of PQ by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that the novel PPY-g-NGE modified GCE exhibited excellent electrochemical performance and electrocatalytic activity to the redox reaction of PQ with comparison to NGE and non-grafted composite of PPY-NGE. The two reduction DPV peaks of PQ at -0.60V and -1.00 V were significantly enhanced at the PPY-g-NGE modified electrode. Under the optimized condition, the reduction peak currents of PQ at the PPY-g-NGE modified electrode were linear over the concentration range from 5.00 x 10(-8) to 2.00 x 10(-6)M with detection limits of 41 nM and 58 nM for Peak 1 and Peak 2, respectively. Besides the good sensitivity, the sensor also exhibited fine stability and strong anti-interference ability due to the well-combination and synergistic effect of polypyrrole and nitrogen doped graphene. (C) 2015 Elsevier Ltd. All rights reserved.