[6] The 1960s marked a period of expansion as Occidental established operations in Peru, Venezuela, Bolivia, Trinidad, and the United Kingdom.

[7] In 1965, Occidental won exploration rights in Libya,[7] where it operated until 1986 when United States economic sanctions led to the suspension of activities.

[9] In 1971, Occidental received approval to build an oil refinery in Canvey Island in Essex, England, but construction ceased in 1975 due to the 1970s energy crisis.

The construction of Soviet port facilities, designed by Hammer's firms, was partially financed by the Export-Import Bank as endorsed by Nixon.

In 2005, Occidental and its partner, Liwa, won 8 out of 15 exploration spots on the EPSA-4 auction, making both companies among the first to enter the Libyan market since the United States lifted its embargo on Libya.

[16] In 1983, Occidental and Ecopetrol, the Colombian state-owned oil company, discovered the giant Caño Limón oilfield in Arauca.

[19] In 1986, the company formed a joint venture with Church & Dwight, which makes Arm & Hammer products, for a potassium carbonate plant at Muscle Shoals, Alabama.

[20] On July 6, 1988, an explosion and subsequent inferno on the company's Piper Alpha platform in the Scottish North Sea, resulted in 167 fatalities in what remains the world's most deadly offshore disaster.

[29] In May 2011, Irani retired as CEO after CalSTRS and Relational Investors, two major shareholders, objected to the company's compensation policies for top executives.

[35] The company also sold its proven and probable reserves of 393 million barrels of oil equivalent (2.40×109 GJ) in Argentina to Sinopec, a subsidiary of China Petrochemical Corporation, and acquired properties in South Texas and North Dakota for $3.2 billion.

[51] Working interest on exploration offshore in Colombia remained under ownership of Oxy in partnership with Ecopetrol, with plans to drill the first well by 2024.

[63] In August 2019, Occidental acquired Anadarko Petroleum for $57 billion, making the deal the world's fourth biggest oil and gas acquisition to date.

[64] In August 2023, Occidental acquired all the outstanding equity of the direct air capture technology company, Carbon Engineering for $1.1 billion.

[66] The company's oil and gas operations are concentrated in two geographic areas: the United States and the Middle East, with some ventures in South America.

[2] The company's oil and gas operations in the Middle East are in Oman, Qatar, and the United Arab Emirates and are via production sharing agreements.

The region produced 251 thousand barrels of oil equivalent (1,540,000 GJ) per day, representing approximately 19% of 2020 total production.

[70] OxyChem, a wholly-owned subsidiary, manufactures polyvinyl chloride (PVC) resins, chlorine, and sodium hydroxide (caustic soda) used in plastics, pharmaceuticals, and water treatment chemicals.

[73] and to remove a provision in the Dodd–Frank Wall Street Reform and Consumer Protection Act that requires disclosure of payments to foreign governments.

[74] In early 2011, the company ceased exploration activities and production operations in Libya due to the growing civil unrest in the country and U.S. sanctions.

In 1978, residents became concerned about unusual health issues in the region, including high rates of cancer and birth defects.

[82][9] On Saturday, October 11, 2008, oleum was accidentally spilled at a facility in Petrolia, Pennsylvania which belonged to Indspec, an affiliate of Occidental Chemical Corporation.

[83] The spill was caused by an auxiliary pump power supply which lacked safety interlocks to prevent tank overfilling.

[85] The government of Bangladesh claimed compensation from Occidental but it left the country handing over the well to Unocal which later sold the interests to Chevron.

On December 13, 1998, 17 civilians, including 7 children, were killed when the Colombian Air Force (CAF) dropped a cluster bomb in the hamlet of Santo Domingo, Colombia, after AirScan, Occidental's security contractor, misidentified it as a hostile guerrilla target.

The plaintiffs claimed that the company violated technical standards and environmental law when it dumped a total of 9 billion barrels (1.4×10^9 m3) of toxic oil by-products, such as cadmium, lead, and arsenic, in drainage basins used by the Achuar people to fish, drink, and bathe.

[96] On March 3, 2010, EarthRights International argued to the United States Court of Appeals for the Ninth Circuit that the case should be litigated in Los Angeles, where the company was headquartered.

In March 2015, the company made a settlement for an undisclosed amount, with the funds to be used for health, education, and nutrition projects in five Achuar communities in the Corrientes River basin.

In September 1972, after he lost an election for the United States Senate in 1970, Gore became the head of Island Creek Coal Company, an Occidental subsidiary.

[110] In 1999, OxyChem achieved Star Status under OSHA's Voluntary Protection Programs as being among the safest work sites in the U.S.[114] On July 6, 1988, the company's Piper Alpha offshore production platform in the North Sea was destroyed when an out of service gas condensate pump was started with its pressure safety valve removed.

The subsequent gas leak, explosion and fire resulted in the deaths of 167 workers in what remains the world's deadliest offshore disaster.