A charging device (1) of a cooling system comprising a coolant fluid; said charging device (1) comprises a supply system (2) suitable to place a reservoir (10) of coolant fluid in fluidic connection with the cooling system; said charging device (1) comprises measurement means (3) of the coolant fluid, comprising a pressure sensor (3a) suitable to measure the pressure of the coolant fluid in the cooling system and a thermometer (3b) suitable to measure the temperature of the coolant fluid in the cooling system; a connection means (4) suitable to functionally and simultaneously connect the supply system (2) and the measurement means (3) to the cooling system; and a control unit (5) suitable to measure at least the quantity of coolant fluid present in the cooling system as a function of said temperature and said pressure.