This article outlines the development of a new hydrodynamic device for probing reactions which occur when ions or uncharged molecules are transferred between an organic and an aqueous solvent. The technique employs a modified form of the confluence reactor, a device recently introduced for mechanistic and kinetic analysis in single phase solvent systems. In this article the cell design, operating conditions and experimental application is described for the transfer of iodine from an organic to an aqueous solution containing iodide ions. Specifically, voltammetric detection is performed in the aqueous phase, with the transport limited current monitored as a function of volume flow rate, using a downstream platinum electrode. The measurements reveal the ability of the technique to access information regarding the transfer of neutral species across the interface between immiscible liquids.