The article addresses the problem of role of the Greek Catholic Eparchy of Mukachevo in the Hungarian Revolution and War of Independence of 1848–1849. Considerable attention is paid to analyze the religious and political activity of Bishop Vasyl Popovych of Mukachevo. The author highlights that the spring events of 1848 created a new situation in Hungary. First in the history of the country a government accountable to the legislation was formed, whose first measures included the abolishment of serfdom. The so-called «April Laws» of 1848 sanctioned by Ferdinand V, the Habsburg king of Hungary had a great influence on the feudal system. The last Diet of Reform Era adopted laws, which paved a way for the bourgeois transformation of the country. It is alleged that one of the most important issues was the determination of the relationship between church and state in spring 1848. This time, the relationship between the Batthyány Goverment and the leaders of the Catholic Church of Hungary was not free from difficulties. The Catholic Church has lost its state religion status. The history of the Eparchy of Mukachevo in the revolutionary events of 1848–1849 is one of the less researched issues. On the basis of analysis of the review of archival sources and historiography of the topic, it is established that the Eparchy of Mukachevo played an exceptional role in support of hinterland of the Hungarian War of Independence. As noted, it had jurisdiction over seven counties in Northeastern Hungary (Zemplin, Ung, Bereg, Ugocha, Sotmar, Sabolch and Maramorosh) and the Hajdú District populated by Rusyn-, Hungarian- and Romanian-speaking believers. Thus, the Greek Catholic clergy had a strategic role to ensure peace between the different peoples. The author comes to the conclusion that Bishop Vasyl Popovych and his prelacy trusted in the goodwill of the Hungarian liberal leaders. The bishop focused on the interests of his eparchy in all circumstances. The years of 1848–1849 were abundant in political and military turns. Popovych was always far from any form of extremism, calmness and prudence controlled his actions. In the end, it is revealed that the Greek Catholic clergy believed: the Hungarian government wanted to create a country, where the Byzantine rite community gets into a favourable, more honoured position. Key words: Greek Catholic Eparchy of Mukachevo, Bishop Vasyl Popovych, Northeastern Hungary, Lajos Kossuth, Catholic Church of Hungary.