This work presents the development of a novel multifunctional microreaction unit made of silicon for application in modular microreaction systems in the chemical engineering. The main working principle of the unit is based on the combination of multilamination and chaotic advection effects. The fabrication of the microreaction unit was performed by KOH wet etching. The numerical investigations were carried out by CFD Research Corporation simulation tool. Modified Villermaux-Dushman reaction was applied to define the mixing performance of the micromixer. Additionally the microreactor unit was characterised by infrared (IR) spectroscopy. The experimental and simulation results describe well the physics of the processes taking place in the microreaction unit. (C) 2003 Elsevier B.V. All rights reserved.