Abstract: A cryogenic breathing system comprises a storage container and a portable container. Both containers, include outer casings and inner containers having small connected openings at their top and providing an evacuable space between their outer casings and inner containers. Material to inhibit heat transfer through the evacuable space is included in this space between the outer casings and inner containers of both containers. The openings of both containers are closed with gas-tight closures fastened to their outer casings. The gas-tight closures can carry, through the single openings in the containers, means to withdraw oxygen for breathing, liquid level indicating means and a mechanical structure to protect the liquid level indicating means, means to admit or withdraw liquid oxygen from the inner container, and means to admit heat to the inner container, as may be desired.