The aim of this work was to characterize both the influence of the gas and the liquid flow rates,on-the, pressure drop generated by static mixers type Sulzer, and on the mass transfer performances of these gas-liquid contactors. The originality of this work rests on the use of the static mixers with a gas continuous phase, Several configurations were studied:, vertical upward flow, vertical downward flow, and horizontal positions with one to five mixing elements. It was concluded that the pressure drop is mainly generated by the gas phase, whatever the configuration-chosen. Moreover, the volumetric mass transfer coefficients k(L)a found were lower than those obtained with the same static mixers used in classic conditions (that is with a liquid continuous phase), but greater than values obtained with classic reactors like bubble columns or packed columns. The efficiency of these gas-liquid reactors was found high, as well as the energy dissipated, unfortunately.