Abstract In this research, a one step and facile approach was used for the synthesis of magnetic multiwalled carbon nanotubes on the surface of diatomite earth as a substrate by chemical vapor deposition (CVD) of methane. The prepared composite was characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM, SEM), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), N2 adsorption – desorption measurement (BET) and Raman spectroscopy analyses. This new material combines the advantages of carbon nanotubes and diatomite in one material. The composite exhibited superparamagnetic properties and was used as a magnetic separable sorbent for adsorption of metal ions from aqueous media. The acid activated sorbent showed fast adsorption kinetic within 10min and maximum Langmuir monolayer capacity of 60mgg−1 for lead ions. The thermodynamic parameters, ΔH, ΔS and ΔG were calculated from temperature-dependent adsorption data indicating adsorption of Pb2+ ions onto the composite material is a spontaneous process. The results suggest that this sorbent is a suitable material for the removal and solidification of metal ions from polluted environmental samples.