Abstract: Device for extracting heat from a hot source (7) and transferring it to an autonomous heat accumulator, which is portable, forming a cold source, this device having the special feature that the said accumulator is formed by an enclosure (1) containing ammonia under conditions such that at least a significant portion of the heat transferred to this accumulator causes the ammonia to pass from the solid state to the liquid state. The device is usable for the thermal control of protective equipment or of leakproof protective suits intended for work in a toxic atmosphere or at high temperature, or also in space.