A Water Activated Battery characterized by a) At least one anode selected from the group consisting of magnesium, aluminum, zinc and alloys thereof; b) A cathode comprising at least one basic copper salt comprising Cu(OH)2combined with a copper salt CuX (with (n−1) the molar ratio between the CuX and the Cu(OH)2in the basic copper salt), such that a discharge reaction in saline versus a Mg anode could be written nMg+Cu(OH)2.(n−1)CuX=Mg(OH)2+(n−1)MgX+nCu) on a skeletal frame, the cathode further comprising a non-hygroscopic soluble, ionically conductive material; c) at least one cavity separating said cathode and said at least one anode; and d) at least one aperture leading to said at least one cavity for the ingress of an electrolyte-forming, aqueous liquid.