It has been shown in the past, that the use of a falling film microreactor is advantageous for operation conditions, during which conventional processing equipment reache its limits. The reactor desing facilitates the development of well controlled, stable meniscei. The very large specific gas/liquid interface (up to 20 000m(2)/m(3)) provides excellent mass transfer capabilities between the phases. Nevertheless, despite the excellent gas/liquid mass transfer that occurs the chemical reactions are limited by the mass transfer within the phases. Commonly, the rate limiting step is the diffusive mass transport within the liquid side. This study investigates the potential of falling film microreactors equipped with structured channels fabricated and are experimentally examined. Besids two reaction plates with straight, unstructured channels (channel width: 600 or 1200 mu m), one plate with fins and one plate with additional grooves in straight 1200 mu m wide channels forming a so-called staggered herringbone mixer are used. Taking carbon dioxide absorption as benchmark rection it is shown that structured channel walls can significantly enchance the mass transfer within the liquid phase. This leads to an increase of the overall performance of the benchmark reaction. Properly chosen channel geometry can increase the conversion by up to 42%. Hence, by using an optimal reaction plate it is possible to more than double the flow rate, without any loss in conversion. (C) 2010 Elsevier Ltd. All rights reserved.