Experimental measurements have been made of mass transfer in a parallel plate cell which has a circular in-line flow inlet. It has been found that the mass transfer coefficient has a maximum value at a point slightly greater than six equivalent diameters downstream from the inlet. For cell Reynolds numbers between 1630 and 2960 this maximum mass transfer coefficient is directly proportional to the Bow rate but the location of the maximum is independent of flow rate. By assuming that the position of the maximum corresponds to the flow reattachment point and considering the mass transfer downstream from that point it has been shown that the local (or average) mass transfer coefficient is proportional to (L.*)-" where L* is the distance downstream from the reattachment point. For turbulent flow n = 0.37 and for laminar/transition motion n is in the range OSCH.60. A preliminary explanation of these results is proposed. NOMENCLATURE A area of anode segment Ii: bulk concentration of ferrocyanide ion F' equivalent diameter Faraday 1, JL K L' limiting current average mass transfer coefficient over anode segment average mass transfer coefficient over a length of electrode L* L distance from the cell inlet L* length of electrode measured downstream from the reattachment point u average velocity ke kinematic viscosity Reynolds number UdJv