Shipboard eddy correlation measurements of DMS air/sea flux and surface ocean concentrations were made out using atmospheric pressure chemical ionization mass spectrometry (API-CIMS).Two cruises were carried out in the North and South Pacific Oceans along cruise tracks from Guam to Oregon,and Manzanillo,Mexico to Punta Arenas,Chile.DMS fluxes were measured for one hour intervals,with 15 minute seawater DMS measurements before and after each flux measurement.Seawater DMS was measured using a membrane to equilibrate clean air with a continuous flow of seawater from the ship’s bow pumping system.DMS gas transfer coefficients (k) were computed from the measured fluxes and observed concentration gradients.These gas transfer coefficients exhibit positive wind speed dependence in general agreement between the two cruises and with earlier estimates.Values of k were mostly in the range between Wanninkhof (1992) and Liss and Merlivat (1986) values,over the wind speed range of 2-8 m/s.