Casalduni is a comune, or municipality, situated in the Campania region of southern Italy. It is located within the Province of Benevento, positioned approximately 60 km northeast of Naples and about 15 km northwest of the city of Benevento.
The town is geographically defined by its location on the slopes of Monte Cicco. It sits on the right bank of the Tammaro river, nestled within the inland landscape of the province.