Gas-liquid mass transfer in micropacked bed reactors is characterized with an automated platform integrated with in-line Fourier transform infrared spectroscopy. This setup enables screening of a multidimensional parameter space underlying absorption with chemical reaction. Volumetric gas-liquid mass-transfer coefficients (k(L)a) are determined for the model reaction of CO2 absorption in a methyl diethanolamine/water solution. Parametric studies are conducted varying gas and liquid superficial velocities, packed bed dimensions and packing particle sizes. The results show that k(L)a values are in the range of 0.12 approximate to 0.39 s(-1), which is about one-to-two orders of magnitude larger than those of conventional trickle beds. An empirical correlation predicts k(L)a in micropacked bed reactors in good agreement with experimental data. (c) 2017 American Institute of Chemical Engineers AIChE J, 64: 564-570, 2018