Sulphuric acid is the most widely produced industrial chemical in the world, used primarily to make fertilizers but also playing essential roles in oil refining, metal processing, mining, battery technology, and dozens of everyday products. Its sheer versatility makes it a backbone of modern manufacturing.
Fertilizer Production
By far the largest share of global sulphuric acid goes toward making phosphate fertilizers. The acid reacts with mined phosphate rock to produce phosphoric acid, which is then converted into calcium and ammonium phosphate fertilizers. These fertilizers supply the phosphorus that crops need to develop strong roots and produce grain. Without sulphuric acid, large-scale food production as we know it would not be possible.
Oil Refining and Gasoline
Petroleum refineries use sulphuric acid as a catalyst in a process called alkylation, which combines smaller hydrocarbon molecules into larger ones that burn more cleanly in engines. The end product, called alkylate, contains virtually no sulphur, aromatics, or olefins and has an excellent octane rating. That makes it one of the most desirable blending components for clean gasoline. Refineries rely on this acid-driven reaction to meet increasingly strict fuel quality standards around the world.
Metal Processing and Steel Cleaning
Before steel can be painted, coated, or shaped into a finished product, its surface needs to be free of rust and mill scale. Sulphuric acid handles this in a step called pickling. Steel is immersed in hot acid, typically around 85°C, which penetrates the oxide layer on the surface, dissolves the corroded material underneath, and lifts the scale away cleanly. This leaves a smooth, reactive surface ready for galvanizing, coating, or further fabrication. Nearly every piece of finished steel you encounter, from car panels to appliances, has gone through some form of acid pickling.
Copper and Mineral Extraction
Mining operations use sulphuric acid to extract copper from low-grade oxide ores in a technique called leaching. The acid is poured or sprayed over heaps of crushed ore, dissolving copper-bearing minerals and carrying the dissolved copper into collection ponds. When air is pumped into the system at the same time, oxygen helps convert all of the dissolved copper into a form that can be efficiently recovered through further processing. This heap-leaching method makes it economically viable to extract copper from ores that would be too low in grade for traditional smelting.
Lead-Acid Batteries
Every conventional car battery contains diluted sulphuric acid as its electrolyte. Unlike the electrolyte in many other battery types, the acid here is not just a passive medium for carrying charge. It actively participates in the chemical reaction that produces electricity. During discharge, the acid reacts with the lead plates to form lead sulphate, and the acid concentration drops. During charging, that reaction reverses: lead sulphate converts back to lead, and the acid concentration rises again. This back-and-forth is why a dying car battery sometimes struggles in cold weather, when thicker, more depleted electrolyte resists the flow of current.
Optimal battery performance tends to fall within a specific gravity range of about 1.24 to 1.30 for the acid solution. Batteries outside that range may deliver weaker starting power or shorter lifespans.
Water and Wastewater Treatment
Industrial facilities that produce alkaline wastewater, such as textile mills, food processors, and concrete plants, use sulphuric acid to bring the pH back to a neutral level before the water can be safely discharged. The acid is added in controlled amounts to neutralize excess alkalinity. Municipal water treatment plants also use it to adjust the pH of drinking water, preventing pipe corrosion and ensuring disinfection chemicals work effectively.
Chemical Manufacturing
Sulphuric acid serves as a starting ingredient or reaction catalyst in the production of a wide range of industrial chemicals. It is used to make hydrochloric acid, nitric acid, synthetic detergents, dyes, pigments, and explosives. The pharmaceutical industry uses it in drug synthesis, and the paper industry uses it in pulp processing. Because it is cheap, stable, and reacts predictably with so many substances, it often turns up in manufacturing chains where you might not expect it.
Household Drain Cleaners
Some of the strongest consumer drain cleaners contain concentrated sulphuric acid, sometimes as high as 93 percent. These products dissolve hair, grease, soap buildup, and organic blockages rapidly by generating intense heat and chemically breaking down the clog material. They are compatible with common pipe materials including PVC, ABS, and cast iron. However, the concentration involved makes them far more hazardous than enzyme-based or alkaline drain cleaners, and they require careful handling to avoid burns or harmful fumes.