Chlorine is one of the largest-volume industrial chemicals in the world, produced at approximately 75 million metric tonnes per year via the chlor-alkali electrolysis process. Unlike mined commodities, chlorine supply is a function of electrochemical manufacturing capacity — not geological reserves — with sodium chloride brine providing a near-inexhaustible feedstock. The chlor-alkali process co-produces chlorine, caustic soda (NaOH), and hydrogen in fixed stoichiometric ratios, meaning the markets for these three products are permanently linked: excess chlorine cannot be produced without creating surplus NaOH, and vice versa. This structural coupling gives rise to the "electrochemical unit" (ECU) pricing concept and periodically creates economic dislocations when the PVC market (chlorine-driven) and the alumina/chemical markets (caustic soda-driven) diverge.

China dominates global chlorine production at approximately 35 million tonnes per year (~47% of world output), driven by one of the largest PVC industries on earth: Chinese apparent PVC consumption reached approximately 20 million tonnes in 2024. The United States produces ~11 Mt/year, predominantly for captive use within its own chemical complex (68% of production in 2022 was captive). Europe, via Euro Chlor member companies, produced 8.04 Mt in 2024 (up 10.2% from 7.29 Mt in 2023 as energy prices normalised post-Ukraine war). The three largest end uses globally are PVC manufacture (~35%), other organic chemical intermediates (~27%), and inorganic chemicals (HCl, hypochlorites, ~18%); water treatment accounts for approximately 8% of global consumption. Chlorine is not on any government critical-minerals list, though EPA assessed US supply as Moderate-High risk specifically for the water sector.

The commodity's risk profile is driven by energy cost and geographic concentration of production. The 2021 trifecta of Winter Storm Uri, COVID-19 demand surge, and planned US facility closures demonstrated how quickly distributed but weather-exposed manufacturing can become a systemic supply bottleneck. European experience from 2022–2023 confirmed that electricity price spikes — a direct consequence of gas supply disruptions — can force rapid capacity curtailment in an energy-intensive industry. Looking forward, growth in Asian chlor-alkali capacity (China, India) is expected to continue, underpinned by expanding PVC and caustic soda demand. In Western markets, chlorine use in pulp bleaching has largely migrated to chlorine dioxide (ECF), while water treatment demand is expected to grow with infrastructure investment.