Chemical hydrides such as MgH₂ are known as high hydrogen containing materials. However their high working temperature and slow kinetics limit their practical application. Mg-based nano-composite materials with nano-Ni catalyst prepared by mechanical milling showed excellent properties, compared with those of Ni, a ball-milled MgH₂ or the mixture of MgH₂ and the nano-Ni catalyst, in terms of the H₂ desorption and absorption. The H₂ absorption capacity at 9 MPa and room temperature in 6 h increased from less than 0.1 wt% for the mixture to 5.0 wt% for the nano-composite material, approaching a maximum of 6.5 wt% in 70 h. The improvement in kinetics is related to the low activation barrier, the large collosion frequency, a short diffusion path length and a high driving force. Carbon-based nano-composite material was synthesized by doping with potassium in superactivated carbon. This material can adsorb 1.6 wt% of hydrogen at room temperature under 5 MPa. This absorption capacity was greater than the value of 1.0 wt% found in potassium-doped graphite. Kinetics of the hydrogen adsorption of the potassium-doped superactivated carbon was considerably improved. The high hydrogen adsorption capacity and the improved kinetics of this system may be derived from the nano-sized graphen and the high surface area.