The fixed-bed microreactor is an important component in many biochip, microsensor, and microfluidic devices. The lattice Boltzmann method (LBM) provides a powerful technique for investigating such microfluidic systems. Accordingly, this study performs LBM-based simulations to examine fluid flows through a fixed-bed microreactor comprising a microarray of porous solids. During operation, the fluid and porous solid species are heated to prompt the chemical reaction necessary to generate the required products. Using the LB model, the flow fields and temperature fields in the microreactor are simulated for different Reynolds numbers, heat source locations, the reacting block aspect ratios, and porosity. A simple model is proposed to evaluate the chemical reactive efficiency of the microreactor based on the steady-state temperature field. The results of this model enable the optimal configuration and operating parameters to be established for the microreactor. (c) 2007 Elsevier Ltd. All rights reserved.