The state of the art in the field of alkali chloride electrolysis for
the production of chlorine, alkali hydroxide and hydrogen is character
ized by the state of development of the membrane cell process. By 1996
about 230 membrane electrolysis plants with a combined NaOH capacity
of about 11 million metric tons will be on line worldwide. This amount
s to roughly one fourth of the world's caustic soda production by elec
trolysis. In this review the main membrane cell technologies, the ion
exchange membranes of different suppliers and anodes and cathodes of t
he membrane cells are described. This first part of the review ends wi
th a look at the problems of brine quality for the membrane cells and
a description of the products chlorine, caustic soda solution and hydr
ogen.