Abstract: Process for the simultaneous production of alkali metal hydroxide and electricl energy. A plurality of hybrid cells (1) are operated in series with an aqueous solution of alkali metal hydroxide introduced as anolyte into an anode compartment of a first hybrid cell (6) at one end of the series and an aqueous fluid medium receptive to alkali metal ions introduced as catholyte into a cathode of a last hybrid cell (7) at an opposite end of the series of cells (1). The anolyte is caused to flow through the anode compartments (3) of the cells (1) in sequence from the first cell (6) to the last cell (7) of the series of cells (1). The catholyte is caused to flow through the cathode compartments (4) in sequence from the last cell (7) to the first cell (6) countercurrently to the flow of anolyte from hybrid cell to hybrid cell of the series of cells (1).