NiHCFs nanoparticles are deposited onto the surface of multiwalled carbon nanotubes (MWCNTs) with a grafted poly(4-vinylpyridine). The as-prepared NiHCF/PV4P-g-MWCNTs composites are characterized by transition electron microscope (TEM) and Fourier transform infrared spectroscopy (FTIR), which confirms the presence of NiHCFs nanoparticles, and shows that NiHCFs nanoparticles are highly dispersed on the surface of MWCNTs in high density. Cyclic voltammograms (CVs) exhibit a great enhancement for NiHCFs/PV4P-g-MWCNTs composites in capacity and stability as ion exchanger by comparison with bulk NiHCF. The capacity for the electrodes modified with NiHCFs/PV4P-g-MWCNTs composites is 69.24 mC/cm(-2) mg, after 100 cycles potential sweeping, these composites modified electrode retains its 98.5% ion-exchange capacity. These composites also exhibit a higher selectivity of for Cs+ over Na+ ions in high concentration of Na+ ion, which is confirmed by X-ray photoelectron spectroscopy (XPS). (C) 2012 Elsevier Ltd. All rights reserved.