A new glassy carbon electrode modified with CeO2 nanoparticles and Nafion (GC/CeO2/Nafion) for electrochemical detection of Malachite Green (MG) was developed and characterized by using square wave anodic stripping voltammetry, batch amperometry and electrochemical impedance spectroscopy. Basic structural features, able to determine intimate relationships between MG and Nafion in solid state at room temperature were evidenced with the use of vibrational analysis carried out by FT-IR. The effect of various anionic and cationic surfactants used to increase the stability of CeO2 nanoparticles suspensions in water on the performances of the modified electrodes was investigated. The influence of CeO(2)nanopowder amount, as well as of the Nafion solution concentration on the electrodes' characteristics was also studied. The sensor with the best response was applied to detect MG in a commercial product commonly used as biocide in aquaria for ornamental fish. (C) 2017 Elsevier B.V. All rights reserved.