Monteroduni is a comune (municipality) in the Province of Isernia in the Italian region Molise, located about 40 km west of Campobasso and about 11 km southwest of Isernia. The town's name derives from the ancient one of the river Volturno, Olotrunus. Sights include the Pignatelli Castle, built by the Lombards in the 9th century and later enlarged under the D'Evoli family. Monteroduni borders the following municipalities: Capriati a Volturno, Colli a Volturno, Gallo Matese, Longano, Macchia d'Isernia, Montaquila, Pozzilli, Sant'Agapito.