Caustic soda, or sodium hydroxide, is used in the manufacture of plastic wrap, soap and paper and is the major ingredient in most oven cleaners and liquid drain cleaners. In chemical manufacturing, it is used in metal processing, oil refining and water treatment. Commercially, it is generally used as either a solid, or a 50-percent aqueous solution.

It constitutes an essential reactant in the production of many useful organic chemicals (more than 32 % of caustic production goes into this application).

Inorganic chemicals like paints, glass and ceramics and uses in fuel cell production and cosmetics are also very important.

The paper, pulp and cellulose industries are major users of caustic soda.

Other areas where caustic is essential are: the food industry, water treatment (for the flocculation of heavy metals and acidity control), the soaps and detergents sectors, the textile sector (as a bleaching agent), mineral oils (preparation of greases and fuel additives) and the synthesis of the synthetic fibre rayon

About four per cent of caustic production is used in the process of refining aluminium from its ore bauxite.

The remainder of the caustic production (more than 17%) has miscellaneous applications, like the synthesis of pharmaceutical compounds, rubber recycling and the neutralisation of acids.