The multi-wall carbon nanotubes (MWNTs) with nickel-phosphorous (Ni-P) layers were prepared by electroless plating method. To obtain the MWNTs with Ni-P layers of high magnetic properties, an effective purification treatment and a pre-treatment procedure were developed. The crude MWNTs, the purified MWNTs and the MWNTs with Ni-P layers were characterized by scanning electron microscope (SEM)/energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). SEM results, TEM images and XRD results indicate that impurities in the crude MWNTs were effectively removed after the purification treatment and a large number of Ni nanoparticles were homogenously coated on the surface of the purified MWNTs. According to the VSM test, the saturation magnetization (Ms) of the MWNTs with Ni-P layers is 91.5 emu/g which is higher than results of other researchers. (c) 2012 Elsevier Ltd. All rights reserved.