Experimental results of the volumetric mass transfer coefficient k(L)a(Ph) in a microstructured rectangular channel (Miprowa (R)) with static mixers are presented. The physical absorption of CO2 in H2O was identified as suitable measuring method. The results include a gas-liquid flow map and the identification of different flow regimes as well as first systematic measurements of the k(L)a(Ph) value as a function of various process settings like gas and liquid flow rate and gas holdup. A first comparison of Miprowa (R) with established gas-liquid contact devices like stirred tank and bubble column is given.