The process of continuous production of dissolved oxygen free water was investigated by means of desorption of dissolved oxygen into fine nitrogen bubbles generated in a novel motionless mixer named Ramond Supermixer(R) (RSM). The pressure drop across the mixer (Delta P-SM) and the volumetric mass transfer coefficient (k(L)a) during the desorption of oxygen from water were measured for various combinations of process variables; liquid and gas velocities and number of mixing units. The k(L)a during absorption was smaller by less than approximately 6% than that during desorption. Specific gas-liquid interfacial areas (a) were measured by the chemical absorption method for a CO2-aqueous sodium hydroxide solution system. Such process characteristics as Delta P-SM, k(L)a, and a were correlated with the process variables and compared with those available in the literature. To further confirm the mass transfer characteristics in RSM, the desorption of oxygen front aqueous electrolyte solutions was also investigated. All the correlations obtained for k(L)a during the desorption of oxygen from water and aqueous electrolyte solutions were compatible to a great higher extent.