In this work, we study the mass transfer of a solute in laminar, two-phase, stratified flow in a circular microchannel. The model developed in our earlier work (Picardo et al., 2015) has been used. We adopt a semi-analytical approach to model liquid-liquid extraction in the circular channel with stratified flow. A bipolar cylindrical coordinate system is employed for an elegant description of the boundaries in the form of iso-coordinate surfaces. The model developed for the circular channel is computationally intensive. We present a methodology to estimate the mass transfer predictions for the 2D circular channel from a 2D channel of rectangular cross-section and a 1D channel i.e. flow between infinite parallel plates. This is analyzed for different carrier phase holdups and fluid properties. It is found that the 1D model can accurately predict the performance of the capillary. Further, we conclude that a more viscous carrier phase results in enhanced mass transfer. © 2018 Elsevier Ltd