Within the ULCOS project, a pilot cell for iron electrowinningis being designed. Electrical energy is used to transformiron ore particles (hematite) suspended in a sodiumhydroxide solution into iron metal and oxygen. The workdeveloped by Labein-Tecnalia is focused on the study ofthe fluid flow for different electrolytic cell configurationsto get knowledge of the interaction between the oxygenbubbles generated during the process and the electrolyteflow. The numerical algorithm used is the finite volume usedin the commercial Computational Fluid Dynamics codeFLUENT. The work developed is focused on vertical andhorizontal parallel plates configurations, to analyze theremoval of oxygen bubbles from the gap between anodeand cathode, and the access of iron ore particles to thecathode. A user subroutine has been developed for theCFD code to compute the mass flow rate of oxygen bubblesgenerated at the anode, as a function of the local currentdensity. A methodology has been developed to analyzethe accessibility of the iron ore particles to the cathode.The knowledge obtained from this work has helped for thedesign of the pilot cell within the ULCOS project.