Magnesium hydroxide is an important component of many technological processes, it has found wide application in food, polymer, light industry, while synthetic magnesium hydroxide has a number of advantages over natural, namely, it has a higher decomposition onset temperature, there are no unwanted impurities in the structure product, it has a higher degree of whiteness, as well as the ability to change the specific surface area (activity) and dispersion of particles during synthesis during synthesis. The way of obtaining magnesium hydroxide by membrane methods can be called the most modern and modernized today, membrane technology is attractive for developers and investors: the processes of separation of liquid media proceed at temperatures close to the ambient tem-perature, their flow is controlled and predictable. At the same time, with regard to the production of electrolytes in modern chemical technology, electromembrane processes, in particular, electrodialysis, are widely used. It is pro-posed to use sea water as a raw material - a natural resource with a changing chemical and bacteriological com-position depending on the depth of sampling, temperature, and natural conditions. The technological scheme of production is represented by the main stage (two-stage fractional precipitation in a batch apparatus with a stirrer) and auxiliary equipment (ultrafiltration unit, bipolar electrodialysis unit, reverse osmosis unit, etc.); developed to separate magnesium hydroxide from seawater while simultaneously solving the problem of the implementation of intermediate products, which ensures care for the environment. The developed production of chemical reagents, in particular, magnesium hydroxide, implements the processes of fractional precipitation and electrodialysis. The re-sults of calculating the economic efficiency of the method indicate the quick payback of the project, the low cost of a kilogram of the target product.