The start of the first alkali chloride electrolysis plants in Bitterfeld-Wolfen was the basis for the further development of a large chemical industry in this region. On 16. October 1894 the first alkali chloride electrolysis was started with vertical Griesheim-Elektron Diaphragm Cells by the ＇＇Che mische Fabrik Elektron＇＇ in Bitterfeld-Sud. An electrolysis plant of the Elektrochemische Werke＇＇ equipped with ＇＇Rathenau-Cells＇＇ which was situated in Bitterfeld-Nord followed in December 1894. The third place, where an electrolysis plant with Aussig Bell Cells, switched on was in 1902 in the ＇＇Agfa Farbenfabrik Wolfen＇＇. The in this region industrial used vertical and horizontal diaphragm cells, the bell cells and the horizontal mercury cells are described. In addition there were several experimental electrolysis cells tested under technical conditions in Bitterfeld. The improvement of the electrolysis processes is shown for the alkalichloride electrolysis and the hydrochloric electrolysis. The development of the chemical companies in this area is presented in a table from the beginning in 1894 until the present.