The absorption of a gas in liquid filled porous particles in gas-solid reactors was studied both theoretically and experimentally. In the theoretical study a micro model, describing mass transport accompanied with reaction inside the particles, was implemented in the macro balance for several asymptotic operation modes. The theoretical study showed that the gas separation can be carried out very efficiently with the liquid filled porous particles, especially for the countercurrent mode of operation. The results of the simulations for the removal of H2S from a gas stream also containing CO2 showed that a very selective absorption process can be obtained. For these kind of selective absorption processes the simulations showed that the residence time of the particles is a crucial parameter.In the experimental part of this contribution the absorption of CO2 in porous gamma-alumina particles filled with water or 2M aqueous solutions of tertiary- or primary alkanolamines was investigated. Experiments were carried out in a gas-solid reactor where the particles were falling down in an empty tube while gas was flowing co-or countercurrently. The conversion for the particles filled with water or the aqueous primary alkanolamine was predicted satisfactorily. For the particles filled with the tertiary alkanolamines, however, the experimental conversions were much higher than theoretically predicted. This difference probably must be attributed to an underestimation of the surface adsorption of CO2 on the gamma-alumina carrier which was very important for the slowly reacting tertiary alkanolamines.