A novel microstructured high efficiency contactor for fluid separation processes, e.g., absorption, desorption or extraction, is developed. A first experimental and numerical investigation of its performance is accomplished using a stripping process as an example. The gas and liquid phase separated by a porous sieve flow countercurrently. The sieve stabilises the gas-liquid interface and permits mass transfer through the holes. The stripping performance is found to be one to two orders of magnitude higher than that of a conventional packed tower. A computational fluid dynamics (CFD) based process model is developed and validated against experimental data. Based on this model, parametric studies are performed to study the impact of liquid and gas flow on separation performance. It is found that mass transfer resistance is mainly concentrated in the liquid phase. Based on the numerical investigations, the contactor geometry is modified to increase the separation performance. The study gives evidence that CFD simulations can be very helpful for the improvement of micro-separation units. (C) 2011 Elsevier B.V. All rights reserved.