Radiolysis of liquid mixtures of O2 and F2 at 77° K with 3-MeV bremsstrahlung produces a mixture of O2F2 and (O2F)n with possibly small amounts of higher oxides. The mixture was converted to pure O2F2at 195° K. Contrary to earlier reports, pure O2F2 is yellow, melts sharply at 119°K, and is diamagnetic. Infrared spectra were obtained of the unpurified product and of O2F2. In the radiolytic synthesis, the G value for generation of F atoms appears to be about 20. Data support the existen:e of O2F2, O2F, O4F2, and unknown oxides of higher oxygen content. As previously reported by others, BF3 reacts with either O2F2 or with mixtures of O2F2 and superoxygen fluorides to produce O2BF2; less stable compounds seem to be produced from the higher superoxides. The infrared and paramagnetic resonance spectra of O2BF4 have been obtained; the X-ray powder pattern shows that the crystals are orthorhombic and isomorphous with NOBF4. © 1969, American Chemical Society. All rights reserved.