Apparatus for heat exchange in a high pressure gas storage tank wherein a heat absorbent gas media circulates within the tank and absorbs or radiates the heat resulting from compression and expansion of gas stored in the on board tank depending upon the mode of operation of the vehicle, the gas media is circulated through a heat exchange unit external to the tank whereby heat is radiated to or absorbed from an environment external to the tank, and an in situ heat exchange device installed within the tank absorbs or radiates the heat from or to the gas stored in the tank as a result of heat exchange through a unit external to the tank.