<p>We present the first ambient measurements of a new marine emission methane sulfonamide (MSAM), along with dimethyl sulfide (DMS) and dimethyl sulfone (DMSO<sub>2</sub>) over the Arabian Sea. Two shipborne transects (W to E, E to W) were made during the AQABA (Air Quality and Climate Change in the Arabian Basin) measurement campaign. DMS mixing ratios were in the range 0.3–0.5 ppb during the first traverse of the Arabian Sea (first leg) and 0.1 to 0.3 ppb in the second leg. In the first leg DMSO<sub>2</sub> was always below 0.04 ppb and MSAM was close to the limit of detection. During the second leg DMSO<sub>2</sub> was between 0.04–0.12 ppb and MSAM was mostly in the range 0.02–0.05 ppb with maximum values of 0.06 ppb. An analysis of HYSPLIT back trajectories combined with calculations of the exposure of these trajectories to <i>chlorophyll a</i> content in the water revealed that most MSAM originates from the Somalia upwelling region, known for its high biological activity. This new marine emission is of particular interest as it contains both sulfur and nitrogen, making it potentially relevant to marine nutrient cycling and particle formation.</p>