The effect of axial flow on the mass transfer through a liquid-liquid interface in a two-layer Taylor-Couette system is studied. The mass transfer of a passive scalar is driven by the diffusion through the boundary, enhanced by the convective mass transport due to the Taylor-Couette vortical flow, which is in turn affected by the axial pressure gradient. Numerical modeling shows that the axial flow obviates the symmetry of the distribution of the local Sherwood number, Sh, in a vortical cell and leads to decrease of its average counterpart. For better physical insight into this effect, simplified kinematic models of the phenomenon were considered. The numerical model shows at Sc = 1 to 10 (Sc being the Schmidt number) that the mass transfer is enhanced by vortical flow in the regions where the motion is directed towards the interface. The axial throughflow makes for elongation of the Taylor vortices in the axial direction and reduces the area of the above regions, thereby increasing the local concentration gradient and reducing the mass transfer rate. Simplified analytical results for Se much greater than I indicate redistribution of the mass flux over the interface compared with the case of Sc = I to 10. The origin of this phenomenon is explained. It is also demonstrated that Sh scales as Pe(1/2) for the whole range of Sc, Pe being the Peclet number of the vortical motion.