This paper analyses the effects of agitation level on the mass transport coefficient in a new electrochemical reactor equipped with reciprocating sieve-plate electrodes. It also presents the results of experimental investigations carried out on laboratory apparatus and in a pilot plant using stainless steel electrodes and an aqueous solution of potassium iodide in the presence of an excess of supporting electrolyte (sodium sulphate). The mass transport coefficient was evaluated from limiting current measurements and current polarisation curves, and correlated with vibrational variables by a controlling dimensionless numbers relationship.