Unitarianism was born in the 16th century in Kolozsvár, in the Principality of Transylvania (it was legalized by the 1568 Diet of Torda and the 1571 Diet of Marosvásárhely). In the beginning it spread in Transylvania, then in the adjacent parts of the Great Plain (Nagyvárad, Simánd, Belényes, Temesvár, Debrecen, Békés, Gyula, Hódmezővásárhely, Makó and Szeged). However, due to Counter-Reformation these dioceses were ceased by the end of the 17th century. Organizing another Unitarian Church (which still exists) started in the second half of the 19th century, following the Act XX of 1848 and the Compromise confirming the former, which proclaimed the Unitarianism a legally accepted religion. Unitarian congregations were established at first in the capital, later in several rural settlements. In 1902 the new congregation established the 9th Deanery (Danubian-Cistibiscan) of the Kolozsvár Episcopate. After the First World War, in 1923 the 9th Deanery was changed into an autonomous church, an Episcopal Vicariate. From 1947 the Episcopal Vicariate of the Hungarian Unitarian Deanery was re-organized. In 1971 the former deanery was elevated to Unitarian Church with the approval of the Presidential Council. The Church is led by a bishop and a general curator.
The ecclesiastical archives was declared a special archives open to the public in 1971. After the arrangement of the records in the 1970s and 1980s, at the beginning of the 1990s the activities of the archives were restricted to preservation. The modernization of the archives started in 1994. In 1997 separate rooms were provided, where as a first step the preservation became safer, then from 1999 the complete fonds revision started and simultaneously catalogues were prepared. The fonds arrangement and processing is done by a researcher with university degree in archival studies. The records prior to 1980 have been taken in and processed since 2001. The institution and a library have had a website since 2002, where among others the catalogue of the classified material can be found.
Address: 1055 Budapest, Nagy Ignác u. 2-4.