Dating back to the union in the Duchy of Nassau in August 1817, before the Prussian Union of September 1817, it is the first United and uniting church in the world. The EKHN is a full member of the Evangelical Church in Germany (EKD), and is based on the teachings brought forward by Martin Luther during the Reformation. The Church President is Volker Jung (since 2009). It is a united church, combining both Calvinist and Lutheran traditions. Member of the Reformed Alliance in Germany. The Protestant Church in Hesse and Nassau is one of 22 churches in the EKD, has 1,602,069 members in 1,184 parishes (December, 2015). The territory of the EKHN includes the territories of the former People's State of Hesse and the Prussian Wiesbaden Region, which now form the southern and western part of the German state of Hesse and portions of the German state of Rhineland-Palatinate (Rhenish Hesse). It's the most important Protestant denomination in this area. The church is a member of the Community of Protestant Churches in Europe.
Institutions of the EKHN are the Church Synod, the church leadership and the church president, who is elected by the General Synod for eight years.
The Protestant Church of Hesse and Nassau was founded in 1946 and 1947 through a merger of three other formerly independent churches: Protestant Church in Hesse, Protestant Church in Nassau, Protestant Church in Frankfurt.