The aim of the present work is to check the specific problem of the determination of mass transfer in developing flows in electrochemical cells. Two types of annular developing flows are studied. The first one is the axial developing flow, downstream of packed beds, which corresponds to the reference flow either from a theoretical point of view or for the comparison with other types of fluid inlet. The second developing flow is the swirling decaying flow induced by a tangential inlet, which allows us to obtain high mass transfer coefficients at the inner wall of the annular cell. Both experimental and numerical study are performed with the aim of establishing suitable assumptions for the numerical resolution of mass transfer problems characterized by high Schmidt number.