Today industrial electrochemical processes are characterized by a high standard of cell design. The advances of the last few years are visible above all in the application of new materials for the separators, the electrodes (including electrocatalytic effective coatings) and for the cell body. For the mathematical modelling of electrochemical membrane reactors it is necessary to evaluate the process parameters, as temperature, electrolyte concentration and velocity, and the electrical potential and the current density distributions. In the present paper the emphasis of the evaluations is to convert the geometrical configuration of special types of pre-electrodes into a model and its solution to evaluate cell voltage and current density distribution. The structure of the models allows us to take into account all possible geometric forms and data of the electrodes. As examples of the application of the models, some special types of louvered electrodes and electrodes made of extended metal are treated. Potential and current density distributions are evaluated and, on the basis of parametric studies some possible constructive changes are discussed.