This study examines the synthesis and characterization of Fe3O4 / reduced graphene oxide nanosheet composites (Fe3O4/RGO NSCs) with different morphology of Fe3O4 and their application in the detection of lead (II). The Fe3O4/RGO NSCs were synthesized via a simple single-step hydrothermal process without the use of templates, with different percentage of RGO (1, 3 and 5%). X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy results confirmed the growth of Fe3O4 in the presence of RGO. Electrochemical properties of the Fe3O4/RGO NSCs electrode were investigated by differential pulse voltammetry (DPV), cyclic voltammetry and electrochemical impedance spectroscopy. These observations confirmed that the optimum percentage of RGO for the fabrication of an electrochemical lead sensor is 3%. The DPV results show that the limit of detection, the limit of quantification (S/N = 3) and the sensitivity are estimated as 0.082 nM, 0.2776 nM and 0.0554 mu A.cm (2) nM (1), respectively, in the linear segment. Results from the reproducibility experiments show that the use of Fe3O4/3% RGO NSCs is feasible for the quantitative detection of certain concentration ranges of Lead (II). (C) 2015 Elsevier Ltd. All rights reserved.