The Debrecen–Nyíregyháza Diocese was established on 31 May 1993 by Pope John Paul II with his Apostolic Constitution beginning Hungarorum gens, which changed the territorial arrangements of the Church Government of the Latin rites in Hungary. The diocese was composed of those parts of the Archdiocese of Eger, the Szatmár and Nagyvárad Dioceses, later the Szeged–Csanád Diocese, which were in Hajdú–Bihar and Szabolcs–Szatmár–Bereg Counties. The bishopric started its activities in modest circumstances in Nyíregyháza in the summer of 1993. In the summer of the following year the office moved to Debrecen, where it settled in the building of a former Catholic elementary school, which was renovated and converted into seat.
The collection of the diocese was established on the initiative of diocesan bishop Nándor Bosák in order to preserve the books and documents of the vacant parishes. In the spring of 1995 an assessment of the books and documents of the vacant parishes of the diocese was made. From October 1995 onwards the books and documents were moved to the building of the bishopric, where they were stored in a room of 60 square metres. The institution, composed of the library and archives, was officially established on 30 December 1995. Due to a lack of space, between November 1999 and February 2000 the entire collection was moved to the ground floor of the adjacent building of the dormitory of the Catholic secondary school (the former Piarist monastery). In 2014 the archives preserve sets of parochial documents from 41 municipalities. The archival holdings cover the 1737–1995 period. The complete archival material is classified at intermediate level and sorted by pieces. The list of fonds was completed by 2014.
Address: 4024 Debrecen, Varga u. 4.