Chloralkali process
![Basic membrane cell used in the electrolysis of brine. At the anode (A), chloride (Cl−) is oxidized to chlorine. The ion-selective membrane (B) allows the counterion Na+ to freely flow across, but prevents anions such as hydroxide (OH−) and chloride from diffusing across. At the cathode (C), water is reduced to hydroxide and hydrogen gas. The net process is the electrolysis of an aqueous solution of NaCl into industrially useful products sodium hydroxide (NaOH) and chlorine gas.](/Images/godic/202501/04/Chloralkali_membrane.svg5005.png")
![Mercury cell for chloralkali process](/Images/godic/202501/04/HgNaOHElectrolysis5005.png")
The chloralkali process (also chlor-alkali and chlor alkali) is an industrial process for the electrolysis of NaCl. It is the technology used to produce chlorine and sodium hydroxide (caustic soda), which are commodity chemicals required by industry. 35 million tons of chlorine were prepared by this process in 1987. Industrial scale production began in 1892.