Caustic soda is a basic feedstock in the manufacture of a wide range of chemicals. It is used as an intermediate and a reactant in processes that produce solvents, plastics, synthetic fibres, bleach, adhesives, coatings, herbicides, dyes, inks and pharmaceuticals. It is also used to neutralise acidic waste streams and the scrubbing of acidic components from off-gases.

Other uses include the saponification or conversion of fat, tallow and vegetable oils in soap manufacture, and in the manufacture of surfactants for detergents. It is used in the petroleum and natural gas industries to remove acidic materials from hydrocarbons and off-gases. In the textile sector, it is used in the chemical processing of cotton and the dying of synthetic fibres.