Market overview

Sodium hydroxide (caustic soda, CAS 1310-73-2) is co-produced with chlorine by electrolysis of brine, so its supply is set by chlorine demand (PVC, MDI, epoxy) rather than by its own markets: alumina refining, pulp and paper, chemicals, soaps and detergents, and water treatment. Olin is one of the largest merchant sellers, and the OlinHuntsman merger pulls more chlorine into captive MDI and epoxy use.

The question this report answers
How will European chlor-alkali closures change caustic soda trade flows and prices?

Market Krystal preliminary estimate (2025)
IMARC: 84.4 Mt (2025). At USD 300-500/t, we estimate USD 25-40 bn. Confidence grade B: one published estimate, checked against volumes or prices.

Market dynamics
– Demand: alumina (17.6%), pulp, chemicals, water treatment
– Supply: co-product of chlorine; Asia 61.7% (IMARC)
– Price and margin: chlorine demand (PVC) drives operating rates
– Regulation: mercury-free membrane cells; energy costs in Europe

Key figures at a glance (third-party, cited)
– Caustic soda market: 84.4 Mt (2025) to 95.9 Mt by 2034 at 1.39% CAGR (volume); alumina 17.6% of demand (IMARC)
– Regional split 2025: Asia-Pacific 61.7%, North America 14.2%, Europe 12.8% (IMARC)
– Jul 2025: Dow announced closure of its Schkopau chlor-alkali and vinyl assets by Q4 2027 (Chemical Processing)

Recent developments among key stakeholders
– Jun 2026: Huntsman and Olin signed an all-stock merger of equals (OlinHuntsman, about USD 12.5 bn pro forma revenue, >USD 400 mn synergies); shareholders approved it and closing is expected in 1H 2027 (ChemXplore)
– Jul 2025: Dow announced it will shut its basic siloxanes plant at Barry, UK (mid-2026), and its Boehlen ethylene cracker and Schkopau chlor-alkali and vinyl assets in Germany (Q4 2027), affecting about 800 jobs (Chemical Processing)

What this means for the market
The merger combines two large positions in this value chain. Integration teams, competitors and customers will reassess capacity, pricing and supplier concentration through the 2027 closing.

How published estimates compare
IMARC reports caustic in tonnes, which is the useful measure for a co-product. Market Krystal adds the chlorine side of the balance (the ECU), which explains price swings, and models the effect of European chlor-alkali closures and of the merger on merchant supply.

Strategic scenarios to 2047
– Base: demand follows GDP, construction and population; China and the Middle East add capacity while Europe rationalises on energy costs.
– Constrained supply: energy shocks, carbon prices and closures in Europe tighten regional supply and widen price spreads between regions.
– Technology transition: low-carbon routes (green hydrogen, electrified crackers, bio-feedstocks, CO2 capture) change cost curves and favour early movers.
The swing factor for Sodium hydroxide (caustic soda) is chlorine demand for PVC and European closures. Signposts: European closure announcements, EU CBAM scope, Chinese capacity additions, energy prices.

What this report delivers
Annual volume (tonnes) and value (USD) for 2026-2035, segmented by form: membrane liquid (50%), flake/solid; application: alumina, pulp and paper, chemicals, soaps and detergents, water treatment, textiles; region: Asia-Pacific, North America, Europe. Each segment is backed by a producer capacity table, price benchmarks for 2020-2025 by grade and region, trade-flow analysis and a supplier risk map. Companies assessed include Olin, Westlake, Formosa Plastics, Shin-Etsu Chemical, Tosoh, Nouryon, INEOS. The 2036-2047 outlook uses three explicit scenarios (base, constrained supply and technology transition) rather than a single extrapolated curve.

Who uses this report
Producers, large buyers, commodity traders and chemical-sector investors.

Why our approach is evidence-based
Most CAS-level market listings publish a single number with no audit trail, and we regularly find figures that contradict their own growth rates or exceed the size of the market they sit inside. Market Krystal works the other way round. We start from physical evidence: plant capacities, production and trade data, company disclosures, regulatory texts and price records. We build volume and price separately and only then compute value. Every third-party figure is cited, every Market Krystal estimate is labelled with its method and a confidence grade, and conflicts between sources are shown rather than hidden. Confidence grades: A = two or more independent sources agree, or government or company data; B = one published estimate checked against volumes or prices; C = no reliable published figure, so the range is built from stated assumptions and narrowed in the full report.

Methodology and delivery
Prepared by the Market Krystal Chemicals Research Team. Each report is built around the buyer’s question: after purchase, a short scope confirmation fixes the priority regions, companies and applications, and the report is delivered within 5-7 business days with the Excel model behind every estimate, so buyers can audit and change the assumptions.

The purchased delivery includes the PDF report, Excel datasets and customization around the buyer’s priority region, company set, application or commercial question.

What this research answers

The study connects production routes, named suppliers, applications, regional demand, trade, pricing drivers and commercial opportunities for this CAS number. Detailed estimates and company analysis remain inside the purchased report.