One stratospheric carbonyl sulfide (COS) vertical profile in the Arctic polar vortex has been retrieved from air samples collected by the MPAE balloon-borne cryogenic sampler on January 18, 1992, at Kiruna, Sweden. The measurements were made in the altitude range 7.5--28.5 km. The upper tropospheric volume mixing ratios of COS were 355¿60 pptv. The stratospheric profile shows that COS is subject to considerable subsidence this time of the year. The lowest VMRs were encountered at around 20 km altitude, while above that height a COS increase was observed. A possible explanation could be reversible uptake of COS by frozen sulfuric acid aerosols. ¿ American Geophysical Union 1995