A microchannel reactor specially designed for periodic operation and a process to deposit a catalyst, -alumina, inside the reactor channels were developed. The hydrodynamics of the reactor was characterised. Although the #ow in the microchannels is laminar, a uniform radial concentration pro"le and consequently a narrow residence time distribution were obtained. Depending on the manufacturing method the Bodenstein number was found to be Bo"ud/D K 70. The catalytic coating had no in#uence on this distribution indicating a uniform deposition of the catalyst within the microchannels. As the inlet function was only slightly modi"ed in the reactors, frequencies of up to 1 Hz could be imposed for periodic operation. The dehydration of isopropanol to propene was chosen as model reaction to study the dynamic behaviour of a microreactor under periodic concentration variations. The kinetics was "rstly studied in a conventional "xed-bed reactor with the catalyst developed for the microreactor. Experimental results con"rmed the theoretically predicted increase of the reactor performance under periodic operation exceeding the maximum obtainable performance under steady-state conditions.