Gas-liquid mass transfer measurements by dynamic absorption in a stirred auto-clave have been performed successively in various single liquid phases and in liquid-liquid mixtures. Data were interpreted through a pseudo-homogeneous model based on Danckwerts surface renewal theory and on continuous liquid-liquid equilibrium due to very fast liquid mass transfer. As a major result, the volumetric mass transfer coefficient k(1)a is clearly increased when adding a dispersed organic phase, with a clear maximum at 3 to 4% of organic volume fraction. Higher enhancement (up to 70%) was performed at high stirring speed and with hydrogen better than with carbon monoxide as the dissolving gas.