Chennai Petroleum Corporation Limited (CPCL) a Group company of Indian Oil Corporation (IOCL) is an Indian state-owned oil and gas corporation headquartered in Chennai, India. It was formed as a joint venture in 1965 between the Government of India (GOI), AMOCO and National Iranian Oil Company (NIOC), having a shareholding in the ratio 74%: 13%: 13% respectively. From the grassroots stage CPCL Refinery was set up with an installed capacity of 2.5 million tonnes per annum (MMTPA) in a record time of 27 months at a cost of Rs. 430 million without any time or cost overrun.

In 1985, AMOCO disinvested in favour of GOI and the shareholding percentage of GOI and NIOC stood revised at 62% and 15.38% respectively. Later GOI disinvested 16.92% of the paid up capital in favor of Unit Trust of India, mutual funds, insurance companies and banks on 19 May 1992, thereby reducing its holding to 67.7%. The public issue of CPCL shares at a premium of Rs. 70 (Rs. 90 to FIIs) in 1994 was oversubscribed to an extent of 27 times and added a large shareholder base of over 90000. As a part of the restructuring steps taken up by the Government of India, Indian Oil Corporation Limited (IOCL) acquired equity from GOI in 2000-01. Currently IOC holds 51.88% while NIOC continued its holding at wax and petrochemical feedstocks production facilities.

CPCL has two refineries with a combined refining capacity of 11.5 million tonnes per annum (MMTPA). The Manali Refinery in Chennai has a capacity of 10.5 MMTPA and is one of the most complex refineries in India with fuel, lube, wax and petrochemical feedstocks production facilities. CPCL's second refinery is Nagapattnam Refinery located at Cauvery basin at Nagapattinam in Panagudi. This unit was set up in Nagapattinam with a capacity of 0.5 MMTPA in 1993 and later enhanced to 1.0 MMTPA.[7] Now this 1.0 MMTPA refinery is being dismantled to increase its capacity to 9.0 MMPTA with cost of 27,000 crores this new project will be completed by 2022 and will boost the company growth further. The main products of the company are LPG, Motor Spirit, superior kerosene, aviation turbine fuel, high speed diesel, naphtha, bitumen, lube base stocks, paraffin wax, fuel oil, hexane and petrochemical feed stocks. The wax plant at CPCL has an installed capacity of 30,000 tonnes per annum, which is designed to produce paraffin wax for manufacture of candle wax, waterproof formulations and match wax. A propylene plant with a capacity of 17,000 tonnes per annum was commissioned in 1988 to supply petrochemical feedstock to neighbouring downstream industries. The unit was revamped to enhance the propylene production capacity to 30,000 tonnes per annum in 2004. CPCL also supplies LABFS to a downstream unit for the manufacture of liner alkyl benzene.

CPCL plays the role of a mother industry supplying feedstocks to the neighbouring industries in Manali. CPCL's products are marketed through IOCL. CPCL's products are mostly consumed domestically except naphtha, fuel oil and lubes which are partly exported.

CPCL has also made pioneering efforts in the field of energy and water conservation by setting up a wind farm and sewage reclamation and sea water desalination plants.

The crude throughput for 2016-17 was 10.256 million metric tonnes (MMT). The company’s turnover for 2016-17 was Rs.40586 crores and the profit after tax was Rs.1030 crores & the crude throughput for 2017-18 was 10.789 million metric tonnes (MMT). The company’s turnover for 2017-18 was Rs.44134 crores and the profit after tax was Rs.912.93 crores.

CPCL's equity shares are listed on the Bombay Stock Exchange and National Stock Exchange of India.

The production line has been affected multiple times due to nature's adversities in form of drought and excessive rains.[8][9][10]

It is categorized as a Miniratna-I company by the government.