(kōtōnō'), city (1992 pop. 536,827), capital of Atlantique prov., S Benin, on the Gulf of Guinea. It is Benin's chief seaport and commercial center. Cotonou's airport and road and rail connections also make it the transportation and communications hub of Benin. The city has small-scale industries; manufactures include palm oil and cake, brewing, textiles, cement and other construction materials, aluminum sheet, beverages, and processed seafood. Motor vehicles and bicycles are assembled, and there are sawmills in the city. Cotonou is a distribution center for petroleum products, and bauxite and iron are exported (primarily to Guinea) from there. Drilling for offshore oil is carried on nearby. Cotonou has research institutes concerned with textiles, tropical agriculture, and geology.
Cotonou was originally a small state that was dominated by the kingdom of Dahomey (see Benin) from the 18th cent. In 1851 the French made a treaty with the Dahomean king Gezo that allowed them to establish a trading post at Cotonou. In 1883 the French navy forcibly occupied the city to forestall British ambitions in the area. The port was enlarged and modernized in the 1960s.