Theoretical equations are reported to calculate the local Sherwood number for a parallel plate electrochemical reactor with a developing flow region under laminar flow conditions. These equations were deduced from analytical velocity profiles according to different proposals, which are compared with the velocity profiles given by the numerical solution of the Navier-Stokes equations. A comparison between the theoretical mass transfer equations with experimental results is also given. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.015302jes] All rights reserved.