Reduced graphene oxide/cupric oxide (RGO/CuO) composites were developed by a simple, eco-friendly sonochemical method. This system has been explored as a potential electrocatalyst toward the electrochemical detection of flutamide. The prepared RGO/CuO composite was confirmed by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and Raman spectra studies. In addition, the electrochemical properties of the prepared electrode were investigated by electrochemical impedance spectroscopy, cyclic voltammetry, and chronoamperometry techniques. The RGO/CuO composite modified glassy carbon electrode (GCE) exhibits high electrocatalytic activity toward the detection of flutamide. The RGO/CuO/GCE modified electrode also detects flutamide with a low detection limit (0.001 mu M), wide linear range (0.005 to 71.32 mu M) and acceptable sensitivity (5.54 mu A mu M-1 cm(-2)). A fabricated sensor showed good selectivity, repeatability, reproducibility and long-term operational stability. Appreciable recoveries were achieved for the detection of flutamide in water and in biological samples, demonstrating the practical feasibility of the RGO/CuO/GCE modified electrode. (C) 2019 The Electrochemical Society.