Exhibit 99.1

For Immediate Release: July 30, 2015

Occidental Petroleum Announces 2nd Quarter 2015 Results

HOUSTON – July 30, 2015 – Occidental Petroleum Corporation (NYSE: OXY) announced core income for the second quarter of 2015 of $165 million ($0.21 per diluted share), compared with $31 million ($0.04 per diluted share) for the first quarter of 2015 and $1.1 billion ($1.38 per diluted share) for the second quarter of 2014. The second quarter of 2015 had reported income of $176 million ($0.23 per diluted share), compared with a reported loss of $218 million ($0.28 per diluted share) for the first quarter of 2015 and reported income of $1.4 billion ($1.82 per diluted share) for the second quarter of 2014.

“We continue to focus on managing our business to be profitable in this current environment by improving margins and increasing production through improved well performance.” said Stephen I. Chazen, President and Chief Executive Officer. “Our second quarter production increased to 658,000 BOE per day from last year’s 580,000 BOE per day, an increase of 13 percent with 78 percent of the increase from oil. The increase was led by Permian Resources, which delivered a 51 percent increase to 109,000 BOE per day, of which oil production grew by 31,000 barrels a day. Operating costs in the U.S. were down to $13 per BOE from $14.50 in 2014. Our second quarter capital was about $250 million lower than the first quarter and over 25 percent lower than the same period last year. Higher production volumes, improved well performance in the Permian, and higher product prices resulted in an increase of about $400 million in operating cash flow before working capital compared to the first quarter. Capital investments continue to be profitable and provide operating cash flow in the current price environment.”

Operating cash flow before working capital changes for the first six months of 2015 was $2.6 billion. The six months working capital changes were $950 million. At December 31, 2014, accounts payable was $5.2 billion, and as of June 30, 2015, it decreased by $1.1 billion to $4.1 billion. This decrease was due to payments related to higher capital and operating spending accrued in the fourth quarter of 2014 but not paid until 2015. Total company capital expenditures for the first six months of 2015 were $3.2 billion. The Oil and Gas segment spent $2.7 billion, with Permian Resources representing 47 percent of the total expenditures, and the remaining $500 million was split between the Chemical and Midstream segments.

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QUARTERLY RESULTS

Oil and Gas

Total oil and gas after-tax results were $108 million for the second quarter of 2015, compared to a loss of $22 million for the first quarter of 2015 and income of $941 million for the second quarter of 2014.

Domestic core after-tax results were a loss of $42 million for the second quarter of 2015, compared to a loss of $89 million for the first quarter of 2015 and income of $409 million for the second quarter of 2014. Compared to the first quarter of 2015, the current quarter domestic results mainly reflected higher crude oil prices as well as improvements in cash operating costs. Year-over-year, the current quarter domestic results reflected significantly lower realized prices for all products, especially crude oil, partially offset by higher crude oil volumes and lower DD&A rates.

International core after-tax earnings were $154 million for the second quarter of 2015, compared to $69 million for the first quarter of 2015 and $561 million for the second quarter of 2014. Compared to the first quarter of 2015, the current quarter international results reflected improved realized crude oil prices and higher sales volumes. Year-over-year, the current quarter international results primarily reflected lower crude oil realized prices, partially offset by higher sales volumes.

For the second quarter of 2015, total company average daily oil and gas production volumes increased by 78,000 barrels of oil equivalent (BOE) to 658,000 BOE from 580,000 BOE in the second quarter of 2014 for continuing operations. Domestic average daily production increased by 25,000 BOE to 333,000 BOE in the current quarter with the majority of the increase coming from oil production, which grew by 26,000 barrels to 205,000 barrels per day, with all of the increase attributable to Permian Resources. The increase in Permian Resources oil production was partially offset by lower oil and natural gas production in the Midcontinent and Other regions. International average daily production increased to 325,000 BOE in the second quarter of 2015 from 272,000 BOE in the second quarter of 2014. The increase in international production is mainly due to operational improvements and the commencement of production from the Al Hosn Gas Project.

On a sequential basis, total company average daily oil and gas production increased by 13,000 BOE. The current quarter domestic average daily production increased by 7,000 BOE compared to the first quarter of 2015. Permian Resources average daily production grew by 11,000 BOE, with 9,000 BOE of the increase coming from oil production growth that increased 15 percent compared to the first quarter of 2015. The increase in Permian Resources oil production was partially offset by lower oil and natural gas production in the Midcontinent and Other regions. The increase in international average daily production of 6,000 BOE compared to the first quarter of 2015 reflected improved production rates at Al Hosn and higher production from

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Dolphin as operations recovered from the first quarter planned maintenance activities. These improvements in production were offset by the loss of Yemen production due to civil unrest and lower cost recovery on production-sharing contracts.

Total company average daily sales volumes were 657,000 BOE in the second quarter of 2015 compared to 637,000 BOE for the first quarter of 2015 and 579,000 BOE in the second quarter of 2014.

Worldwide commodity prices for the second quarter of 2015 improved from the first quarter of 2015, but were still significantly lower than the second quarter of 2014. The average quarterly WTI and Brent marker prices increased to $57.94 per barrel and $63.50 per barrel, respectively, in the second quarter of 2015, compared to $48.63 per barrel and $55.17 per barrel, respectively, for the first quarter of 2015, but decreased from $102.99 per barrel and $109.77 per barrel for the second quarter of 2014. Worldwide realized crude oil prices improved by 12 percent to $54.55 per barrel for the second quarter of 2015, compared with $48.50 per barrel for the first quarter of 2015, and decreased by 45 percent compared with $99.30 per barrel in the second quarter of 2014. Although worldwide NGL prices increased slightly to $18.06 per barrel in the second quarter of 2015, compared with $17.96 per barrel in the first quarter of 2015, as a percentage of WTI, the realization decreased 16 percent. The second quarter 2015 NGL prices decreased by 56 percent, compared with $40.98 per barrel in the second quarter of 2014. Domestic natural gas prices decreased 16 percent in the second quarter of 2015 to $2.09 per MCF, compared with $2.49 per MCF in the first quarter of 2015, and fell by 50 percent compared with $4.15 per MCF in the second quarter of 2014.

Chemical

Chemical pre-tax core earnings for the second quarter of 2015 were $136 million, compared to $139 million in the first quarter of 2015 and $133 million in the second quarter of 2014.

Midstream and Marketing

Midstream pre-tax core earnings for the second quarter of 2015 were $84 million, compared to a loss of $5 million for the first quarter of 2015 and income of $130 million for the second quarter of 2014. The increase in earnings compared to the first quarter of 2015 reflected improved marketing margins due to the widening of WTI and LLS differentials, and higher pipeline income from both domestic and foreign pipelines. Compared to the second quarter of 2014, the current quarter reflected lower gas plant results due to the decline in NGL prices, reduced pipeline income as a result of lower Dolphin Pipeline gas sales, and lower power generation income due to extended planned outages.

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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 region 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 in support of Occidental’s businesses. The company’s wholly owned subsidiary OxyChem manufactures and markets chlor-alkali products and vinyls.

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; reorganization or restructuring of Occidental’s operations; not successfully completing, or any material delay of, field developments, expansion projects, capital expenditures, efficiency projects, acquisitions or dispositions; 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; 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 2014 Form 10-K. Occidental posts or provides links to important information on its website at www.oxy.com.

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Contacts:

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

or

Investors:
Christopher M. Degner
212-603-8111
christopher_degner@oxy.com

On the web: www.oxy.com

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Occidental Petroleum Corporation

Q2 2015 Earnings Release Schedules Index

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.

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