Liquid–liquid two-phase flow patterns in a serpentine glass microchannel have been studied using a camera with very high shutter speed. The phase system is equilibrated water−succinic acid−n-butanol system. Observed flow patterns have been classified into seven different types: slug flow, slug and droplet flow, droplet flow, unstable annular flow, annular flow, annular dispersed flow, and fully dispersed flow. Two different ways of introducing the aqueous and organic phases into the microchannel have been studied. Flow regime maps are presented and discussed. Voronoi diagrams of the flow regime maps are also presented.