In this paper, we report the green synthesis of the Cu/Fe3O4 nanoparticles using Silybum marianum L. seeds extract and their application as magnetically separable nanocatalyst for the reduction of nitroarenes. Our method is clean, nontoxic and environment friendly. The synthesized nanocatalyst is characterized by XRD, TEM, EDS and UV-visible techniques. UV-visible spectroscopy is used to monitor the kinetics of the Cu/Fe3O4 nanoparticles formation. The results from Fourier transform infrared spectroscopy showed that the C=O and C-O groups in the plant seeds extract played a critical role in capping the nanoparticles. The expected reaction mechanism in the formation of nanoparticles is also reported. The catalyst is recoverable by magnetic decantation and could be reused several times without significant loss in catalytic activity. (C) 2016 Elsevier Inc. All rights reserved.