A simple mathematical model has been developed and validated for the dynamic behaviour of a pilot plant absorber with random packing (stainless steel construction, column diameter: 0.08 m, height of packing zone: 1.3 m, random packing: 15 mm ceramic spheres). The model is based upon film theory, axial dispersion, and rate enhancement. Simplifications are made which are justified for the conditions of the experimental investigations in the pilot plant of this work. Simulation of other conditions like for example acid gas removal in industrial applications will require additional consideration of water evaporation and of the energy balance. The experimental part concentrates on measurements of the residence time distribution of several sections of the pilot installation. Combination of the different transition functions allows the determination of the dynamic behaviour of the packing zone. The model has been validated by experiments with absorption of CO2 into water and into carbonate solution at moderate conditions (5 bar(abs), 290-333 K). Although the mass transfer parameters have been strictly prescribed according to theory, the simulation results agree well with experimental data. (c) 2006 Elsevier B.V. All rights reserved.