Design of microstructured reactors with thermal control function is investigated through numerical simulation. It consists of one middle channel for handling chemicals and two other channels attached to its top and bottom for cooling purpose. Three designs are examined. Reactor A uses simple straight channels. In reactor B, chaotic flow is applied to the middle channel, and in reactor C chaotic flow is applied to all the three channels. Results show that in comparison with the straight channel, the Nusselt number in current design is greatly improved through chaotic flow. Rapid mixing is also achieved. Potential application of the design for continuous exothermic process is analyzed. For reactor A, it is not workable as the temperature of the chemical solution continuously increases over the channel. In comparison, for both reactors B and C the temperature can be well controlled within the required range. As the coolant flow in reactor C is also chaotic, it provides a higher heat removal capacity. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.