Chemistry of the Antarctic Boundary Layer and the Interface with Snow (CHABLIS) is a Natural Environment Research Council (NERC) and Antarctic Funding Initiative (AFI) funded project, aimed at studying the chemistry of the Antarctic Boundary Layer in greater detail, and for a longer duration, than has previously been attempted. Field measurements were carried out at the British Antarctic Survey station, Halley, at the Clean Air Sector Laboratory (CASLab). Year-round measurements began in February 2004, and a summer campaign focussing on oxidants ran during January/February 2005, after which CHABLIS fieldwork ended. The dataset contains Ion Chromatograph analysis data (major ions from Cascade Impactor sampling, from high volume air sampling (HIVOL) and low volume air sampling (LOVOL) at Halley). Access to this dataset is now public.