Within the ULCOS project, a pilot cell for iron electrowinning is being designed. Electrical energy is used to transform iron ore particles (hematite) suspended in a sodium hydroxide solution into iron metal and oxygen. The work developed by Labein-Tecnalia is focused on the study of the fluid flow for different electrolytic cell configurations to get knowledge of the interaction between the oxygen bubbles generated during the process and the electrolyte flow. The numerical algorithm used is the finite volume used in the commercial Computational Fluid Dynamics code FLUENT. The work developed is focused on vertical and horizontal parallel plates configurations, to analyze the removal of oxygen bubbles from the gap between anode and cathode, and the access of iron ore particles to the cathode. A user subroutine has been developed for the CFD code to compute the mass flow rate of oxygen bubbles generated at the anode, as a function of the local current density. A methodology has been developed to analyze the accessibility of the iron ore particles to the cathode. The knowledge obtained from this work has helped for the design of the pilot cell within the ULCOS project.