A dual mode electrochemical system comprises a first electrode capable of storing hydrogen, a second electrode, a substantially electrically insulating and substantially ionically conducting membrane interposed therebetween and an electrolyte. In a first mode, upon introduction of water and electricity the dual mode electrochemical system electrolyzes the water in the presence of the electrolyte and produces hydrogen and oxygen across the membrane. The hydrogen is stored in the first electrode. In a second mode, upon introduction of an oxidant to the second electrode the dual mode electrochemical system produces water and electricity by reacting the stored hydrogen and the oxidant across the membrane.