In this work, the effects of the presence of surfactants in the liquid phase and the hydrodynamic regime of the bubble flow on the oxygen transfer rate were investigated in an electroflotation process in batch mode. The volumetric mass transfer coefficient LK a and the oxygenation capacity were evaluated to improve the performances of the electroflotation process in terms of oxygena-tion. In order to evaluate the liquid-side mass transfer coefficient LK , the volumetric mass transfer coefficient LK a was dissociated into LK and the specific interfacial area (a) since the last one was obtained from the gas hold-up and the bubble diameter. The effect of Reynolds number which define the hydrodynamic of the bubble flow has been also studied. Models of LK a and LK have been established to show the effects of the hydrodynamic parameters and liquid phase characteristics on the oxygen transfer rate.