This paper reports High-Density Cold Heat Transportation Material used as heat transport fluid for cooling system. The form of the material was particles that consisted of paraffines processed to gel. Paraffines were used as a phase change materials. This material was suspended in water. In this paper, thermal properties and heat transfer characteristics of this slurry were evaluated by using a differential scanning calorimeter and a double-tube-type heat exchanger. The paraffines in the slurry froze without causing supercooling and the amount of heat exchange of the slurry increased in comparison with that of water.