Oca is an ancient city and bishopric in present-day Anatolia (Asiatic Turkey), restored as a Latin titular see.
Its site is located in Biga district of Çanakkale Province.
Oca was a city in the Roman province of Hellespontus, in Asia Minor. It was a bishopric, suffragan of the Metropolitan Archdiocese of Cyzicus.
It was nominally restored as a Latin titular bishopric of the lowest (Episcopal) rank in 1933.
No incumbents are recorded yet.