Mokissos is the formal name for a now inactive Diocese of the Greek Orthodox Church.
Mokissos was an ancient Byzantine city (Turkish: Kırşehir), located in western Cappadocia at the foot of what is now known as the Hasan Dag, southeast of Koloneia. The Byzantine Emperor Justinian I rebuilt the ruined city, renamed Justinianoupolis (a name last attested in 692), and elevated it to the rank of ecclesiastical metropolis, with an eparchia that stretched south of the Halys River (Turkish: Kızılırmak), the longest river of Asia Minor. The bishopric survived under its original name through the Byzantine period.
The extensive site, which lies in a protected valley, today, contains the remains of nine churches, streets, and unidentified civic buildings.
The current Bishop of Mokissos is Demetrios, who is protosyncellus of the Greek Orthodox Metropolis of Chicago.
Coordinates: 38°11′08″N 34°12′26″E / 38.18556°N 34.20722°E