Ciomadul is located in the southeastern Carpathians, at the end of the Călimani (Kelemen) - Gurghiu (Görgényi) - Harghita (Hargita) volcanic chain, and is also known as Ciomadu. The gorge of the Olt River separates Ciomadul from the Harghita Mountains. The towns of Băile Tușnad and Bixad are close to the volcano, and a road leads up the volcano from the southeast and goes past the Mohos swamp to the St. Ana lake. The basement of the volcano is formed by flysch of Cretaceous age and by older volcanics; in some places volcanic rocks overlie fluvial deposits.