The development of an automated microreaction system (AuMmuRes) is described allowing a systematic screening of process parameters for the design and optimization of chemical processes in the liquid regime. Besides parameter screening, the microreaction system is also dimensioned for automated small-scale production in the kilogram range. By the adaptation of suitable actors and control techniques an active regulation of process parameters is possible. Pulsation-free actors, integrated sensors (temperature, pressure, flow, density), interfaces for analysis (HPLC, online spectroscopy), and a well-proven process control system are essential parts of the automated microreaction system. Microfluidic structures with improved flow and mixing performance as well as microstructured flow-through sensors for monitoring pressure and mass flow have been developed and integrated into the microreaction system. As a test reaction the nitration of 2-(4-chlorobenzoyl-)benzoic acid was considered. In order to handle this highly corrosive reaction all components that are in direct contact with the reagents consist of corrosion-resistant material. (C) 2004 Published by Elsevier B.V.