Microreactors have gained great interest in a large variety of chemical reactions due to two major advantages: excellent heat transfer in the case of highly exothermic or endothermic reactions and enhanced mass transfer. Considering an enhancement of mass transfer one has to distinguish between homogeneous liquid-phase reactions and heterogeneous reactions. Microreactors for homogeneous reactions are based on entwined microchannels in the range of 10-300 mum within special micromixers. Heterogeneous applications cover the field of heterogeneous catalysis and solid-phase supported organic syntheses. Since polymer supports have seen an increasing interest in the field of solid-phase supported organic syntheses and ion exchange applications in the last years, in this study the use of a novel polymer/carrier microreactor for these applications is presented. The microreactor consists of a megaporous inorganic carrier material with irregular shaped channels and an immersed polymer phase which is used as a solid support for organic reactions. Investigations on dynamic ion exchange were conducted for different exchanging ions and different reactor systems. Furthermore the solid-phase supported selective reduction of cinnamaldehyde is studied, a model reaction for the important class of reductions of aldeyhdes in organic chemistry. All results show an enhanced mass transfer to the active sites of the polymer and higher effective rates using the novel microreactor in comparison to commercially available ion exchange resins. (C) 2004 Elsevier B.V. All rights reserved.