Abstract: A power generation system utilizing an electrochemical cell comprising a reactive metal anode, a cathode spaced from the anode and an electrolyte comprising an aqueous solution of the hydroxide of the reactive metal is disclosed. The hydroxide concentration in the electrolyte is controlled by contacting the electrolyte with at least one complex comprising a hydrogen fluoride adduct to a fluoride salt to form at least one compound of the reactive metal which is insoluble in the electrolyte. The insoluble compound is separated from the electrolyte and the electrolyte is recirculated to the electrochemical cell.