In this work, the flow hydrodynamic characteristics and the mass transfer performance of immiscible fluids in the packed microchannels are investigated experimentally. Water-kerosene system is used for visually identifying the flow hydrodynamic characteristics in PMMA microchannels, and water-succinic acid-n-butanol is chosen for investigating mass transfer performance in stainless steel microchannels. Quartz sand micro-particles are used as packing particles. In packed microchannels, high liquid-liquid dispersions can be obtained, and the diameter of droplets produced in the packed microchannel can be even less than 10 mu m. It ensures better mixing performance and larger effective interfacial area of two immiscible fluids, and improves the mass transfer performance obviously. Compared to the extraction efficiency (46-61%) in the non-packed microchannel, it can reach 81-96% in the packed microchannel. The effects of packing length, micro-particle size on liquid-liquid dispersions and extraction efficiency are investigated. The pressure drop and the specific energy dissipation in the packed microchannels are also discussed. (C) 2010 Elsevier Ltd. All rights reserved.