A sensitive hydrazine electrochemical sensor based on Zinc oxide nano-wires (ZnO NWs) synthesized from low temperature hydrothermal method has been fabricated using an add-on technique. The morphology, crystalline structures, and composition of synthesized ZnO NWs were characterized by scanning electron microscopy, X-ray powder diffraction, energy dispersive spectroscopy, and high-resolution transmission electron microscopy. The batch-made ZnO NWs were used as electrocatalytic material and modified on the gold electrode surface through a printing-like method via Nafion to obtain Nafion/ZnO NWs/Au hydrazine electrochemical sensor. To optimize performance, the effect of the ZnO modified quantity on sensitivity was evaluated by cyclic voltammetry, electrochemical impedance spectroscopic, and single-potential amperometry techniques. The results show that the optimum ZnO NWs modified quantity is about 170 g cm(-2). The optimized Nafion/ZnO NWs/Au hydrazine electrochemical sensor has a high sensitivity of 3.8 mu A . mu M-1 cm(-2), a short response time of 3 s, and a very low detection limit of 0.0144 mu M with a linear hydrazine concentration response range from 3.0 to 562 mu M. (C) 2014 The Electrochemical Society. All rights reserved.