The present paper deals with a theoretical investigation of a potential step at a channel electrode. The study consists in the numerical solution of the partial differential equations relevant to the transient mass balance in the vicinity of the electrode, taking into account the convective term. Although such an equation has been investigated previously for both heat and mass transfer, we present the results obtained with the help of two packages relying upon either the numerical method of lines (DSS/2) or a derived Gear technique (LSODA). Results of the simulation — concentration profile and wall concentration gradient — are reported and a comparison with previous results is carried out. Both packages used yield very similar current variations which are observed to be in a good agreement with experimental data.