The Infrared spectra of IOS02F, BrOS02F, HOS02F, DOS02F, Br3S03F and Ca02S03F are obtained at 80Β°K. Detailed vibrational assiqnments and structural conclusions are presented. I. INTRODUCTTn"' Since the discovery of a convenient route to peroxy-disulfuryldifluoride, S206F2, by Dudley and Cady 1) . in 1957, many interesting fluorosulfates are now known. Of particular interest to us have been the halogen fluorosulfates and their derivatives. The halogen fluorosulfates of the types XS03F, with X = F, Ce, 6r and I, and X(SOSF)S, with X = Br and I, and the haloqen oxyfluorosulfates X02S03F, with X = CQ and I, are all readily obtained by the direct interaction of a 2)-7) halogen or halogen oxide with S206F2. Most of them were first obtained by G.H. Cady and his coworkers. Even though no detailed structural study has been reported on any of these compounds, vibrational spectroscopy, in particular Raman spectroscopy, 8)-lo) ha! afforded some structural information. For the halogen(I) fluorosulfates of fluorine, chlorine and bromine, covalent structures of the type XOS02F, with --a) permanent address -University of Glasgow, Glasgow, Scotland , CeOS02F4), BrOS02F16), IOSO,F") and Ce02S03F were synthesised according to published methods. BrOS02F and