Preparation of multi-wall carbon nano-tubes (CNTs) is successfully demonstrated via a metal dusting (MD) process, in which a steel coupon and CO–CO2 mixed gas are the only reactants needed. During the process, fresh Fe–Ni nano-particles are produced spontaneously and continuously from the steel, and consequently catalyze the growth of the CNTs. Post-treatments, including heating in air at 550°C and etching in boiling nitric acid, are used to purify the as-prepared multi-wall CNTs. The microstructure modification due to the post-treatments are examined with a transmission electron microscopy. The possibility of utilizing the MD-produced CNTs as a hydrogen storage material is also explored in this study.