Disclosed herein is a method and device for production of a new long-term storage-stable allotropic modification of oxygen, tetraoxygen O4, using a combination of known chemical reactions into one technological sequence, including chemical interaction of negative and positive oxidation state oxygen compounds. The method involves production of dioxygen difluoride by oxidation of molecular oxygen with fluorine, followed by the reaction of dioxygen difluoride with alkali metal peroxide, forming tetraoxygen O4. Tetraoxygen is stable in its liquid state up to a temperature of +40° C. and can be used for the oxidation of rocket fuel, long-term compact storage of oxygen, and many other purposes.