Falling film microreactors, which provide very high specific interfacial area, have become a promising solution to the fast and strongly exothermic/endothermic gas-liquid reaction systems. A computational fluid dynamic simulation of the two-phase flow for a falling film microreactor is presented using the volume of fluid (VOF) model. The hydrodynamic characteristics, from both 2-D and 3-D simulations, including liquid film thickness, velocity, pressure and shear stress profiles, are analyzed. 2-D simulation is adopted for the study of the relationship of liquid flow rate and film thickness, as well as the effects of gas flow rate, surface tension, liquid viscosity and pressure difference on the liquid flow rate. 3-D simulation is necessary to provide the comprehensive flow profiles. Although the system is in the laminar flow regime, the liquid film features a wavy structure and the velocity profiles are complex. (C) 2011 Elsevier Ltd. All rights reserved.