Velocity fields in a rotating disc contactor (RDC) with single-phase flow have been measured using a Laser Doppler Velocimeter (LDV) and simulated with computational fluid dynamics software. Simulated velocity profiles are in fair agreement with the experimental ones. Both experimental and calculated results show that there exist vortices between adjacent rotating discs and between adjacent stator rings in the flow system. The vortex between stator rings enhances mixing and mass transfer in a compartment, while the vortex between discs is the main factor causing axial mixing. In order to suppress the axial mixing thus enhancing the mass transfer efficiency in the extraction column, a modified rotating disc contactor (MRDC) is proposed. Simulated velocity profiles in the new extraction column have shown that the axial mixing between the discs has been effectively eliminated.