A review; microstructured reactors are mainly characterized by their very-high surface to vol. ratio compared to traditional chem. reactors. Multichannel microreactors having channel diams. in the order of ten to several hundred micrometers have sp. surface areas up to 50,000 m2/m3. This value is roughly two orders of magnitude higher compared to conventional prodn. vessels. Due to the small reactor dimensions diffusion times are short and the influence of mass transfer on the rate of reaction can be efficiently reduced. As the heat transfer performance is greatly improved compared to conventional systems, higher reaction temps. are admissible leading to reduced reaction vols. and amt. of catalyst. Therefore, microstructured reactors are esp. predestinated for fast, highly exothermic or endothermic chem. reactions. [on SciFinder (R)]