Fuel cell or metal air cell has its oxygen (air) electrode plunged completely into the electrolyte which has an O2 dissolution capacity at 1.280 bar and ambient temp. of >=0.05 ml O2/ml electrolyte and the O2 necessary for the operation is introduced in dossed manner into the electrolyte from oxygen or air physically or physicochemically dissolved therein, and continually replaced during operation. The cells are free of losses during operation, and provide a stable power supply with time. In place of the three phase reaction zone of prior art, a two phase zone develops further improving stability.
