Cidyessus (Κιδύησσος) was a city of some importance, west of Ammonia in west-central Phrygia, in the territory of the Setchanli Ova, or Mouse Plain; this large and fertile valley projects far into Phrygia Salutaris, but the city was in Phrygia Pacatiana.
Three ancient bishops of the see of Cidyessus are mentioned in extant contemporary documents: Heraclius participated in the Council of Chalcedon in 451; Andreas in the Second Council of Nicaea in 787; and Thomas in the Photian Council of Constantinople (879).
- Sophrone Pétridès, "Cidyessus" in Catholic Encyclopedia (New York 1908)
- Michel Lequien, Oriens christianus in quatuor Patriarchatus digestus, Paris 1740, Vol. I, coll. 801-802
- Raymond Janin, v. Cidyessus, in Dictionnaire d'Histoire et de Géographie ecclésiastiques, vol. XII, Paris 1953, col. 828
- Annuario Pontificio 2013 (Libreria Editrice Vaticana 2013 ISBN 978-88-209-9070-1), p. 869