Microporous tube-in-tube microchannel (MTMC) emulsification is a continuous high-throughput technique for producing emulsions. The MTMC emulsification device could reach a maximum throughput capacity of 5 L/min of emulsion droplets. In this study, the effects of surfactant, phase physical property (viscosity), operation conditions (flow rate, temperature), and structural parameters of the MTMC (micropore size, annular channel width) on average droplet diameter of an O/W emulsion were systemically investigated. The results indicated that soybean oil-in-water (O/W) emulsions could be successfully prepared by using SDS and Tween 80 as surfactants in the MTMC. The formed droplet diameters were almost constant below the critical velocity, over which the droplet diameter drastically increased, and more polydispersed emulsions were formed. The average size of the O/W emulsion droplets decreased with the reduction of surfactant concentration, temperature, viscosity of the dispersed phase, micropore size and annular channel width, as well as the increase of overall flow rate. Furthermore, the characteristics of the emulsification pressure drop through the MTMC were also explored. (C) 2013 Elsevier B.V. All rights reserved.