The vehicles driven by water and iron Tokyo Institute of Technology, Professor Kiyoshi Otsuka and his group developed a new technology for supplying pure hydrogen to PEFC vehicles.Otsuka and his group have proposed a simple, safe and environmentally benign technology for the storage, transport and supply of hydrogen to PEFC vehicles. The technology is based on a very simple redox reaction of magnetite (Fe3O4 + 4H2 <==> 3Fe + 4H2O). The reduced iron oxide (Fe metal) pellets is packed in the cassettes. The cassettes will be mounted on PEFC vehicles. Addition of water into the cassettes would produce pure hydrogen and regenerate Fe3O4. The hydrogen could be supplied directly to the PEFC on board without any purification treatment of CO.The theoretical amount of hydrogen being stored is 4.8weight% of Fe. This corresponds to 4.2 kiloliter(STP) hydrogen to be produced per one litter of Fe. The storage capacity of hydrogen is relatively high compared to the hydrogen absorbing alloys easily obtained. The iron and iron oxide are nontoxic and fuel is just water, there is no danger of explosion when the vehicles collide. The weight of iron to be loaded and its volume are 105 kg and 13.3 liter, respectively, for 500km drive for vehicles.The redox performance of iron oxide was very much enhanced by the addition of metal elements (3 mol%) such as Al, Ga, Cr, Mo, and Zr. The redox reaction could be operated at a low temperature 300oC.Otsuka and his group are developing more efficient materials based on iron oxides as well as an unit apparatus with the cassette container and water injection equipment.