Exhibit 99.1

Occidental Petroleum Announces 1st Quarter 2017 Results

·    Net Income of $117 million or $0.15 per share

·    Permian Resources average daily production of 129,000 BOE, up 5 percent from the previous quarter

·    Chemical segment’s Ingleside ethylene cracker started in February, on schedule and on budget

HOUSTON — May 4, 2017 — Occidental Petroleum Corporation (NYSE:OXY) today announced reported net income of $117 million, or $0.15 per diluted share, compared with a reported loss of $272 million, or $0.36 per diluted share, for the fourth quarter of 2016. Lower costs, improved crude oil prices and the increase in caustic soda prices and sales volumes during the first quarter resulted in increases to income and cash flow on a sequential basis.

“Our focus remains on areas that generate the best returns and we are seeing improvements in margins across all of our businesses,” said President and Chief Executive Officer Vicki Hollub. “Permian Resources continues to be a growth engine for our company, with a 5 percent improvement in production this quarter, reflecting increased drilling activity and well productivity in the Delaware Basin.”

QUARTERLY RESULTS
Oil and Gas

Total average daily production volumes were 584,000 barrels of oil equivalent (BOE) for the first quarter of 2017. Permian Resources average daily production volumes came within guidance and improved by 6,000 BOE from the prior quarter to 129,000 BOE in the first quarter of 2017 due to increased drilling activity and well productivity in the Delaware Basin. In April 2017, Occidental completed the sale of its South Texas gas properties. First quarter of 2017 average daily production volumes, adjusted to exclude South Texas, were 559,000 BOE, including domestic production volumes from ongoing operations of 278,000 BOE.

Internationally, average daily production volumes were 281,000 BOE for the first quarter of 2017. Production volumes for the first quarter of 2017 reflected Colombia pipeline disruptions, as well as planned maintenance at the Al Hosn Gas and Dolphin operations. All of these assets are currently operating at full capacity.

Oil and gas pre-tax income for the first quarter of 2017 was $220 million, compared to $17 million for the fourth quarter of 2016. The increase in oil and gas results reflected higher oil prices

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and lower DD&A rates in the first quarter of 2017, partially offset by lower international sales volumes.

For the first quarter of 2017, average WTI and Brent marker prices were $51.91 per barrel and $54.66 per barrel, respectively. Average worldwide realized crude oil prices were $49.04 per barrel for the first quarter of 2017, an increase of 9 percent compared with the fourth quarter of 2016. Average worldwide realized NGL prices were $21.59 per barrel in the first quarter of 2017, an increase of 18 percent compared to the fourth quarter of 2016. Average domestic realized natural gas prices were $2.68 per MCF in the first quarter of 2017, compared to $2.39 per MCF in the fourth quarter of 2016.

Chemical

In February, OxyChem and its joint venture partner, Mexichem, began operations of an ethylene cracker in Ingleside, Texas. The project was completed on schedule and on budget. The cracker, which is operated by OxyChem, has the capacity to produce 1.2 billion pounds of ethylene per year and provide OxyChem with an ongoing source of ethylene for manufacturing vinyl chloride monomer, which Mexichem will use to produce polyvinyl chloride (PVC) resin and PVC piping systems. The companies have a 20-year supply agreement.

Chemical pre-tax income for the first quarter of 2017 was $170 million. Pricing for caustic soda continued to increase as global demand remained robust and supply was limited due to industry-wide planned and unplanned outages. In addition to the impact of higher caustic soda prices, chlor-alkali margins improved more than anticipated due to lower natural gas costs compared to original forecasts. Compared to pre-tax income of $152 million in the fourth quarter of 2016, the increase resulted from higher realized caustic soda prices and volumes. Production and sales volumes increased seasonally from the fourth quarter of 2016.

Midstream and Marketing

Midstream pre-tax results for the first quarter of 2017 were a loss of $47 million, compared to a loss of $48 million for the fourth quarter of 2016. Compared to the fourth quarter of 2016, the first quarter of 2017 reflected lower foreign pipeline income due to planned maintenance, offset by higher gas processing income due to higher NGL prices.

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About Occidental Petroleum

Occidental Petroleum Corporation is an international oil and gas exploration and production company with operations in the United States, Middle East and Latin America. Headquartered in Houston, Occidental is one of the largest U.S. oil and gas companies, based on equity market capitalization. Occidental’s midstream and marketing segment gathers, processes, transports, stores, purchases and markets hydrocarbons and other commodities. The company’s wholly owned subsidiary OxyChem manufactures and markets basic chemicals and vinyls. Occidental posts or provides links to important information on its website at www.oxy.com.

Forward-Looking Statements

Portions of this press release contain forward-looking statements and involve risks and uncertainties that could materially affect expected results of operations, liquidity, cash flows and business prospects. Actual results may differ from anticipated results, sometimes materially, and reported results should not be considered an indication of future performance. Factors that could cause results to differ include, but are not limited to: global commodity pricing fluctuations; supply and demand considerations for Occidental’s products; higher-than-expected costs; the regulatory approval environment; not successfully completing, or any material delay of, field developments, expansion projects, capital expenditures, efficiency projects, acquisitions or dispositions; uncertainties about the estimated quantities of oil and natural gas reserves; lower-than-expected production from development projects or acquisitions; exploration risks; general economic slowdowns domestically or internationally; political conditions and events; liability under environmental regulations including remedial actions; litigation; disruption or interruption of production or manufacturing or facility damage due to accidents, chemical releases, labor unrest, weather, natural disasters, cyber-attacks or insurgent activity; failure of risk management; changes in law or regulations; reorganization or restructuring of Occidental’s operations; or changes in tax rates. Words such as “estimate,” “project,” “predict,” “will,” “would,” “should,” “could,” “may,” “might,” “anticipate,” “plan,” “intend,” “believe,” “expect,” “aim,” “goal,” “target,” “objective,” “likely” or similar expressions that convey the prospective nature of events or outcomes generally indicate forward-looking statements. You should not place undue reliance on these forward-looking statements, which speak only as of the date of this release. Unless legally required, Occidental does not undertake any obligation to update any forward-looking statements, as a result of new information, future events or otherwise. Material risks that may affect Occidental’s results of operations and financial position appear in Part I, Item 1A “Risk Factors” of the 2016 Form 10-K.

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Contacts:

Media:
Melissa E. Schoeb
713-366-5615
melissa_schoeb@oxy.com

or

Investors:
Richard A. Jackson
713-215-7235
richard_jackson@oxy.com

Anthony J. Cottone
212-603-8111
anthony_cottone@oxy.com

On the web: www.oxy.com

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Occidental Petroleum Corporation

Quarter 1 2017 Earnings Release Schedules Index

SCHEDULE 1

Occidental Petroleum Corporation

Summary Highlights

SIGNIFICANT TRANSACTIONS AND EVENTS AFFECTING EARNINGS

Occidental’s results of operations often include the effects of significant transactions and events affecting earnings that vary widely and unpredictably in nature, timing and amount. These events may recur, even across successive reporting periods. Therefore, management uses a measure called “core results,” which excludes those items. This non-GAAP measure is not meant to disassociate those items from management’s performance, but rather is meant to provide useful information to investors interested in comparing Occidental’s earnings performance between periods. Reported earnings are considered representative of management’s performance over the long term. Core results are not considered to be an alternative to operating income reported in accordance with generally accepted accounting principles.

SCHEDULE 2

Occidental Petroleum Corporation

Segment Results Before Tax Allocations

(Amounts in millions, except per share and effective tax rate amounts)