A non-aqueous electrolyte secondary battery is disclosed, which hardly causes deterioration of its properties at high temperatures. The battery has a chargeable and dischargeable cathode, a chargeable and dischargeable anode, and a non-aqueous electrolyte and includes a substance which produces water with an increase in temperature in any one of the cathode, the anode, the non-aqueous electrolyte, other elements, and voids in the battery. Examples of the substance which produces water include hydroxides and compounds having water of crystallization.