A microelectrochemical reactor (MECR) was developed, fabricated and tested for electrochemical detection and analysis of potassium ferricyanide. The application and advantage of hydrodyamic focusing by using a background electrolyte has been demonstrated. High conversions were observed with this new technique and the cell was further developed using computational modelling to improve the conversions and study the effect of lead in length and focusing ratios in order to minimise the diffusion effects in a microchannel over the electrode. It was demonstrated that by increasing the lead in length inter stream diffusion increases leading to less amount of material being addressed at the electrode and hence lower conversions were obtained.