Abstract: The invention pertains to a cooling device for cooling breathing gas in a respiratory protection device with a heat collector exposed to the breathing gas stream. Such a cooling device is to be improved such that it can be prepared for cooling at any desired time prior to putting the respiratory protection device into operation, and that cold storage of a coolant is not required. The improvement is achieved by designing the heat collector as a storage tank for an evaporable liquid, which can be connected to an evacuated adsorbent container such that the liquid will evaporate while absorbing heat of vaporization, and its vapor is adsorbed on an adsorbent contained in the adsorbent container while releasing heat of adsorption and heat of condensation, wherein the adsorbent container is designed as a cooling body that is arranged outside the breathing gas stream and is intended to release the heat into the surroundings.