Member states of OPEC

Iran, officially the Islamic Republic of Iran, and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the northeast, Afghanistan to the east, Pakistan to the southeast, and the Gulf of Oman and the Persian Gulf to the south. With a population of over 92 million, Iran ranks 17th globally in both geographic size and population. It is divided into five regions with 31 provinces. Tehran is the nation's capital, largest city, and financial center.

Algeria, officially the '''People's Democratic Republic of Algeria''', is a country in the Maghreb region of North Africa. Spanning over , it is the largest country in Africa and the tenth largest in the world. It is bordered to the northeast by Tunisia; to the east by Libya; to the southeast by Niger; to the southwest by Mali, Mauritania, and Western Sahara; to the west by Morocco; and to the north by the Mediterranean Sea. With a population of over 47 million, Algeria is the tenth-most populous country in Africa. Its capital and largest city is Algiers.

Iraq, officially the Republic of Iraq, is a country in West Asia. Located within the geo-political region of the Middle East, it is bordered by Saudi Arabia to the south, Turkey to the north, Iran to the east, the Persian Gulf and Kuwait to the southeast, Jordan to the southwest, and Syria to the west. The country covers an area of and has a population of over 46 million, making it the 58th largest country by area and the 31st most populous in the world. Baghdad, home to over 8 million people, is the capital city and the largest in the country.

Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in West Asia. Located in the centre of the Middle East, it covers the bulk of the Arabian Peninsula and has a land area of about 2,150,000 km2 (830,000 sq mi), making it the fifth-largest country in Asia, the largest in the Middle East, and the twelfth-largest in the world. It is bordered by the Red Sea to the west; Jordan, Iraq, and Kuwait to the north; the Persian Gulf, Bahrain, Qatar and the United Arab Emirates to the east; Oman to the southeast; and Yemen to the south. The Gulf of Aqaba in the northwest separates Saudi Arabia from Egypt and Israel. Saudi Arabia is the only country with a coastline along both the Red Sea and the Arabian Gulf, and most of its terrain consists of arid desert, lowland, steppe, and mountains. The capital and largest city is Riyadh; other major cities include Jeddah and the two holiest cities in Islam, Mecca and Medina. With a population of almost 32.2 million, Saudi Arabia is the fourth most populous country in the Arab world.

Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and various islands and islets in the Caribbean Sea. It comprises an area of , with a population estimated at 31.8 million in 2025. The capital and largest urban agglomeration is Caracas. The continental territory is bordered on the north by the Caribbean Sea and the Atlantic Ocean, on the west by Colombia, Brazil on the south, Trinidad and Tobago to the north-east, and on the east by Guyana. Venezuela consists of 23 states, the Capital District,

Libya, officially the State of Libya, is a country in the Maghreb region of North Africa. It borders the Mediterranean Sea to the north, Egypt to the east, Sudan to the southeast, Chad to the south, Niger to the southwest, Algeria to the west, and Tunisia to the northwest. With an area of almost , Libya is the fourth-largest country in Africa and the Arab world, and the 16th-largest in the world. The country claims 32,000 square kilometres of southeastern Algeria, south of the Libyan town of Ghat. The capital and largest city is Tripoli, located in the northwest and containing over a million o

Kuwait, officially the State of Kuwait, is a country in West Asia. With a coastline of approximately , it is situated at the head of the Persian Gulf in the northeastern edge of the Arabian Peninsula, bordering Iraq to the north and Saudi Arabia to the south. Kuwait is geographically the closest Gulf country to mainland Iran (separated only by a small Iraqi coastline). The country is a small city-state; most of the population reside in the urban agglomeration of Kuwait City, the capital and largest city. , Kuwait has a population of 4.82 million, of which 1.53 million are Kuwaiti citizens whil

The Republic of the Congo, also known as Congo-Brazzaville, the Congo Republic or simply Congo, is a country located on the western coast of Central Africa to the west of the Congo River. It is bordered to the west by Gabon, to the northwest by Cameroon, to the northeast by the Central African Republic, to the southeast by the Democratic Republic of the Congo, to the south by the Angolan exclave of Cabinda, and to the southwest by the Atlantic Ocean.

Gabon ( ; ), officially the Gabonese Republic (), is a country on the Atlantic coast of Central Africa, on the equator, bordered by Equatorial Guinea to the northwest, Cameroon to the north, the Republic of the Congo to the east and south, and the Gulf of Guinea to the west. It has an area of and a population of million people. There are coastal plains, mountains (the Cristal Mountains and the Chaillu Massif in the centre), and a savanna in the east. Libreville is the country's capital and largest city.

Equatorial Guinea, officially the Republic of Equatorial Guinea, is a country on the west coast of Central Africa. It has an area of 28,000 square kilometres (11,000 sq mi). Formerly the colony of Spanish Guinea, its post-independence name refers to its location both near the Equator and in the African region of Guinea. As of 2025, the country has a population of 1,853,559, over 85% of whom are members of the Fang people, the country's dominant ethnic group. The Bubi people, indigenous to Bioko, are the second largest group at approximately 6.5% of the population. Its capital is Ciudad de la Paz, replacing former capital Malabo in 2026, while its largest city is Bata.