Olin created the company for the purpose of supplying the area's coal mines and limestone quarries with explosives.

Olin's New Haven and East Alton plants employed about 17,000 workers each — producing the guns and small-caliber ammunition needed during World War II.

[8][9][10] Long before its association with Olin, Mathieson Alkali Works began business in Saltville, Virginia, and a year later acquired its neighbor, the Holston Salt and Plaster Corp. Saltville became a quintessential company town, where they produced chlorine and caustic soda, and in the process leached methylmercury (by the company's own estimates, up to 100 pounds per day) into the soils and the North fork of the Holston River.

[13][14][15] Afterward, the corporation diversified its interests into a wide variety of businesses, including plastics, cellophane, bauxite mining, automotive specialties, powder actuated nailing tools, and home construction.

The company manufactured phenoxy herbicides and anti-crop agents for Fort Detrick under contract to the U.S. Army Chemical Corps.

[20] Nearly 30 years prior to Olin acquiring Mathieson Chemical, a muck dam collapsed, sending a 30-foot wall of water, mud, mercury, and alkali down the Holston River valley into the company town of Palmertown, a community of Saltville, Virginia.

[22] Olin was the first U.S. corporation to be prosecuted for violations of the arms embargo, and in 1978 was convicted for selling Winchester rifles to private dealers in South Africa.

Olin transferred its ball propellant manufacturing plant to General Dynamics subsidiary St. Marks Powder in 1998.

[3] On March 27, 2015, Dow Chemical Company announced that it would spin off its chlorine and epoxy businesses and merge them with Olin Corporation.

[35] On October 5, 2015, Olin successfully acquired Dow's U.S. Gulf Coast Chlor-Alkali and Vinyl, Global Chlorinated Organics, and Global Epoxy business units, in addition to 100 percent interest in the Dow Mitsui Chlor-Alkali joint venture.

[5] In 2016, Olin Corp, which was still based in Missouri, announced it was laying off 100 workers, or around 80% of the facility's workforce, at a factory north of downtown Henderson, also halting chlorine production at the site.

It also stopped production of lye, with the facility to be remade into a bleach factory and distribution center for various industrial chemicals.

[43] In 2022, Olin created a joint venture with Plug Power Inc., to produce 15 tons of "green" hydrogen per day at a plant in Louisiana, to be operational by 2023 according to the company.

[citation needed] The former Olin Corporation headquarters in East Alton, after being purchased by the Wieland Group, were razed in 2022.

"[citation needed] The company produces chemicals such as chlorine, caustic soda, and hydrogen through a process involving the electrolysis of salt.

[citation needed] The chemical branches of the business also produce vinyls, epoxies, chlorinated organics, bleach, and hydrochloric acid.