Novel nanocomposites of xanthated Fe3O4-chitosan grafted onto graphene oxide (xanthated Fe3O4-CS-GO) were successfully synthesized for the first time using an amidation reaction. The xanthated Fe3O4-CS-GO was used to remove Cu(II) from aqueous solutions. The xanthated Fe3O4-CS-GO was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometry, and energy dispersive X-ray spectroscopy. The Cu(II) adsorption isotherms for the xanthated Fe3O4-CS-GO fitted the Langmuir isotherm model. The maximum Cu(II) adsorption capacity of the xanthated Fe3O4-CS-GO was 426.8 mg g(-1), which is much higher than the maximum adsorption capacities of other adsorbents that have been described in the literature. This was attributed to xanthated Fe3O4-CS-GO having abundant functional groups. The xanthated Fe3O4-CS-GO could be regenerated using ethylene diamine tetraacetic acid, and could easily be removed from a liquid using an external magnetic field. These features would allow secondary pollution of the environment to be avoided more easily than is the case for other adsorbents. Cu(II) was adsorbed from aqueous solutions quickly and efficiently by the xanthated Fe3O4-CS-GO complex, suggesting that xanthated Fe3O4-CS-GO may be an ideal candidate for removing Cu(II) from wastewater. (C) 2016 Elsevier B.V. All rights reserved.