As a practical utilization of the potential cold energy of liquid hydrogen (LH 2 ), the authors have been developing a LH 2 refrigerator van called Musashi-9 by modifying a 4-ton diesel truck. It has been found that LH 2 on board refrigerator van Musashi-9 can be used not only as the cold energy to keep the cooled goods at the temperature of 0 ± 5°C but also as the fuel for the van. It has also been found that the NO x emission can be reduced to as much as 53% of the future target value required in the 13-mode driving pattern for the emission evaluation requirement in Japan.