Caustic soda: Overview
Alumina, paper, soap: the world's workhorse alkali
Alumina, paper, soap: the world's workhorse alkali What this tab covers What the chemical is, how big its market is, what it is used for (with shares, volumes, why it wins and what could replace it), and its chain from raw material to end user. Ends with three things to remember.Caustic soda is sodium hydroxide, made with chlorine by electrolysing salt brine: every tonne of chlorine brings 1.13 t of caustic. World output is about 90 Mt a year (100% basis), roughly 47% of it in China. It dissolves bauxite to make alumina, pulps wood, makes soap and neutralises acids across industry. Because its supply depends on chlorine demand rather than its own, caustic prices swing hard. Unlike chlorine, it ships easily as a 50% solution, so it is a genuinely global traded commodity.
Volume about 90 Mt a year (100% NaOH basis, 2025, indicative, derived from about 80 Mt chlorine x 1.13; no Euro Chlor or World Chlorine Council world total is published) Market value about $35-40 billion (2025, indicative: 90 Mt x about $400/dmt Asian and US export prices) Growth about 2-3% a year, led by alumina in Asia and chemicals in India (indicative) Mysteel Nov 2025 (China output 42.62 Mt); Argus Chlor-Alkali and Derivatives Oct 2025 (prices); world total derived (indicative)Key uses
| Use | Share | Annual volume | Why this commodity | Alternatives |
|---|---|---|---|---|
| Organic chemicals (propylene oxide, epoxy, polycarbonate, pharma and agro intermediates) | 20% | about 18 Mtbasis | Caustic neutralises the HCl formed in chlorinated routes, saponifies esters and makes phenol and other sodium salts. Many chlorine-based processes consume caustic on the same site, so the ECU partly balances itself. industry splits (indicative) | Soda ash or lime for some neutralisation Non-chlorine routes that need no alkali |
| Alumina refining (Bayer process) | 17% | about 15 Mtbasis | Hot caustic dissolves alumina from bauxite. Refiners lose 50-150 kg caustic per t alumina depending on bauxite quality, so alumina growth in China, India, Indonesia and Australia drives demand. Price spikes hurt refiners first. industry splits (indicative) | None at scale for the Bayer process Partial recovery from red mud |
| Pulp and paper | 13% | about 11.7 Mtbasis | Kraft pulping uses sodium hydroxide and sodium sulphide to dissolve lignin; mills recover most chemicals but need make-up caustic and use it in bleaching. industry splits (indicative); USGS MCS 2026 (Soda ash) | Recovered soda ash causticised with lime ('chemical caustic') |
| Inorganic chemicals (sodium silicate, hypochlorite, sodium cyanide, phosphates) | 12% | about 10.8 Mtbasis | A cheap, pure sodium source and strong base for making salts. industry splits (indicative) | Soda ash for silicates and phosphates |
| Soaps, detergents and textiles | 15% | about 13.5 Mtbasis | Saponifies fats to soap, neutralises LAB sulphonic acid in detergents and mercerises cotton. This is a large share in India and South-East Asia. industry splits (indicative); Alchempro 2025 (India end uses) | Potassium hydroxide (dearer) Soda ash in some detergents |
| Water treatment | 5% | about 4.5 Mtbasis | Adjusts pH, removes metals and regenerates ion-exchange resins. industry splits (indicative) | Lime Magnesium hydroxide |
| Other (food, petroleum refining, mining, batteries) | 18% | about 16.2 Mtbasis | Includes cathode precursor co-precipitation for lithium-ion batteries, a fast-growing niche. industry splits (indicative) | Ammonia in some precipitation steps |
From raw material to user
- Salt brine About 1.5 t of salt per t of caustic (1.65-1.75 t per t chlorine).
- Electrolysis Membrane cells give about 32% caustic solution directly; diaphragm cells give 10-12% with salt.
- Evaporation Concentrated to 48-50% liquid, the main traded form; about 0.5-1 t steam per t (indicative).
- Flakes and prills Further dehydrated to 98-99% solid for long-distance and small users.
- Distribution Ocean tankers carry 50% lye from the US Gulf, NE Asia and Middle East; Indian producers supply by road tanker.
Made from (commodity table)
NaCl SaltThree things to know
- Caustic soda is a by-product of chlorine demand: each t of chlorine yields 1.13 t, so caustic supply rises when PVC is strong.
- Prices swing widely: US Gulf export caustic was about $850/dmt in Oct 2022 and $390-440/dmt in Oct 2025 (Argus).
- India had 6.40 Mt of capacity in FY2024-25 and made 5.05 Mt, and is now a modest net exporter.