Tetramethylammonium ozonide is an oxygen rich compound with the chemical formula . It consists of tetramethylammonium cations () and ozonide anions (). The compound is a free radical with one unpaired electron.
It can be created through the metathesis reaction with caesium ozonide (CsO<sub>3</sub>) in a liquid ammonia solution.
Tetramethylammonium ozonide was found to be stable; it forms into transparent red crystals, and only decomposes above 75 ðC.