Résumé : A method is described for the routine determination of barium in sea water by graphite-furnace atomic absorption spectrometry. Barium is separated from the main sea- water cations by collection on a cation-exchange resin. The barrium is extracted into nitric acid from a portion of the resin for injection into the pyrolytically-coated graphite furnace. The method is satifactory for the low μg l-1 levels of barium present in ocean water, with recoveries {slanted equal to or greater-than}99% and a relative standard deviation of <5%. © 1987.