Abstract: A system for producing elemental magnesium (Mg) from seawater having a cell with a pair of permeable membranes which define an anodic compartment with an anode therein and a cathodic compartment with a cathode therein. A space is provided between the pair of membranes through which seawater is allowed to freely flow. A source of electric current is connected to the anode and cathode to charge the compartments in order to cause ions within the seawater to pass from the space into the compartments whereby positive and negative ions are separated. The electric charge associated with the cathode causes the seawater to decompose into H2 and (OH—)2 and positively charged magnesium ions within the seawater pass through the cathodic permeable membrane to combine with the (OH—)2 to form magnesium hydroxide precipitates.