A device for recovering the refrigeration units of LNG (liquid natural gas) used as fuel in vehicles, said device configured for being installed in said vehicles comprising a tractor and a trailer or semi-trailer with a refrigerated cabin, said device comprising: - a first heat exchanger, configured to be placed on said tractor between a LNG tank and a LNG gasification circuit (12, 18), said LNG being sent to a motor configured to drive said tractor, said first heat exchanger being configured to transfer the refrigeration units of the LNG to a heat transfer fluid, so as to use said refrigeration units in order to remove thermal energy from said refrigerated cabin configured to be installed on the trailer or semi-trailer, - a second heat exchanger, configured to be placed inside said refrigerated cabin and configured to be installed on the trailer or semi-trailer, which is also configured to transfer the refrigeration units from said heat transfer fluid to the air inside said refrigerated cabin; - a closed intermediate circuit, in which said heat transfer fluid flows, which includes an apparatus for moving said heat transfer fluid, systems (4, 5) for fast connecting and disconnecting, without leakages, the pipes of said intermediate circuit configured to be installed on said tractor from the pipes of said intermediate circuit installed on said trailer or semi-trailer, the device being characterized in comprising a tank for storing the heat transfer fluid, said heat transfer fluid being of the gas type, such as helium, or of the liquid type, such as glycol or mixtures of glycol with water or other liquids, wherein the tank is configured for recovering said heat transfer fluid and for maintaining the intermediate circuit at a certain operating pressure value. - a first heat exchanger, configured to be placed on said tractor between a LNG tank and a LNG gasification circuit (12, 18), said LNG being sent to a motor configured to drive said tractor, said first heat exchanger being configured to transfer the refrigeration units of the LNG to a heat transfer fluid, so as to use said refrigeration units in order to remove thermal energy from said refrigerated cabin configured to be installed on the trailer or semi-trailer, - a second heat exchanger, configured to be placed inside said refrigerated cabin and configured to be installed on the trailer or semi-trailer, which is also configured to transfer the refrigeration units from said heat transfer fluid to the air inside said refrigerated cabin; - a closed intermediate circuit, in which said heat transfer fluid flows, which includes an apparatus for moving said heat transfer fluid, systems (4, 5) for fast connecting and disconnecting, without leakages, the pipes of said intermediate circuit configured to be installed on said tractor from the pipes of said intermediate circuit installed on said trailer or semi-trailer, the device being characterized in comprising a tank for storing the heat transfer fluid, said heat transfer fluid being of the gas type, such as helium, or of the liquid type, such as glycol or mixtures of glycol with water or other liquids, wherein the tank is configured for recovering said heat transfer fluid and for maintaining the intermediate circuit at a certain operating pressure value.