Iran will assume the presidency of the Organization of Petroleum Exporting Countries (Opec) for the first time in 36 years.
The country's oil minister was elected as Opec president at a one-day meeting of the group, which is made up of 12 oil producing states.
Masoud Mir-Kazemi will hold the presidency from 1 January 2011.
Iran, which takes over from Ecuador, is Opec's second-largest oil producer and holds about 10% of world oil reserves.
At the meeting in Vienna, Opec also agreed to keep its oil production target unchanged at about 24.8 million barrels a day.
US light crude ended Thursday trading down 32 cents to $82.69.
Brent crude finished 11 cents lower at $84.53.