This work presents an analysis of the dynamic behaviour of a plug flow electrochemical reactor for a step change in flow rate. The mathematical model takes into account the temporal variation of the mass transfer coefficient of the electrochemical reaction by means of an empirical expression with one parameter. To simplify the numerical solution of the general differential equation different assumptions are made. Thus, analytical equations of the transient current response are obtained. The theoretical treatments are compared with experimental results, obtained from copper deposition in a parallel-plate electrochemical reactor, in order to determine the reliability and the correlation capability of the mathematical models. The influence of the empirical parameter values on the performance of the reactor is also analysed.