Abstract In the 1920s, American chemist Gilbert Newton Lewis made assumption about the existence of O4 molecule. In the 1970s, scientists discovered O4 dimers using infrared and visible spectroscopy. In the 1980s, scientists proposed the existence of metastable covalent O4 molecule through theoretical calculations. The covalent O4 molecule as an allotrope of oxygen is considered to be a potential high energy density material. In 2007, By evaluating the stability of covalent O4 molecule, scientists have determined that covalent O4 molecule can be detected experimentally. The discovery history of O4 is a process from guess to confirmation. It is also a process of continuous progress of science and technology and the evolution and development of scientific thoughts.
