Seawater injection into reservoirs is a common method to enhance oil recovery. In order to avoid corrosion in pipes, the oxygen has to be removed from the seawater. This study focuses on the use of silver cathodes in electrochemical cells for oxygen removal, and the physical parameters that affect the efficiency of this process. Three electrochemical cells have been constructed and tested with packed bed cathodes made up of pure silver particles and silver plated brass spheres. Experimental results showed that silver was a suitable cathode material for oxygen removal. The most important parameter for optimizing cell performance was the depth of the cathode chamber. In addition, the thickness of the silver plating is also an important parameter to adjust since a too-thin layer results in erosion giving rise to galvanic corrosion between brass and silver, which reduces the efficiency of the cell.