Multi-walled carbon nanotubes were synthesized using methane as carbon source and Colombian natural limonite ore as catalyst precursor. Catalyst was evaluated in reduced form in the reaction decomposition of methane at 700°C. Multi walled carbon nanotubes were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Finally, TEM micrographs showed that the MWCNTs have inner diameters ranging from 5 to 30 nm and outer diameters up to about 60 nm, and several microns in length.