In the development of the electrolysis technique for iron,the cell-design step is crucial to ensure that the resultsobtained on smaller scale experiments are scaled-up toindustrial size. Design criteria, based on the theorem ofequipartitioned irreversibility, are proposed for the alkalineelectrowinning process. One of the specific features ofthe process is the treatment of a multiphase electrolyte, agenuine breakthrough for electroextraction processes. Eachof the unit-operations necessary to obtain the separation ofthe iron and oxygen from iron oxide are depicted togetherwith the corresponding physical limitations and availabletechnologies. Optimal solutions to obtain uniform andsteady variation of each of the involved phenomena canbe readily deduced from this approach and a cell-design isproposed.