Although the history of the village of Demnia dates back to the 16th century (when it was recorded that the village was burnt down by Tatars in 1515), for many years it belonged to the parish of Mikolajov. It was only after the end of the First World War that a parish exposition was established, and in 1935 an independent parish.

In March 1911, the Lvov consistory gave permission for the construction of a chapel, which in time became a branch church and finally the parish church of Our Lady of Czestochowa. However, this construction encountered many problems on its way. Although the walls of the new building were already erected in 1912, financial problems were encountered. A year later, thanks to a grant from the Lviv governorate and the Lviv consistory, the building could be sealed. However, the choir, roof and floor were still missing.

At the same time, the pastor in Mykolayiv changed, which also delayed work on the Demni temple. Work was resumed just before the outbreak of the First World War and it was possible (thanks to another donation) to complete the chapel, in which services began to be held. Later that year, however, the building was damaged by Russian troops. In later years, Austrian soldiers were stationed there. They renovated the chapel and an unknown artist painted the temple. After the war, a vicarage was built in Demni.

The church was closed after the end of the Second World War and converted into a kolkhoz warehouse and later into a gymnasium for the school, which was located in the vicarage building. When the building was still functioning as a gymnasium, the roof was repaired, but a year later (1990) the hall was closed. Since then, the building, still in relatively good condition, has stood empty.

Architecture
The brick church in Demni was built on a cruciform ground plan. It consists of a two-bay nave, a single-bay chancel closed with a trilateral and short transept arms. The nave has a tower built on a square plan. A rectangular sacristy was added to the chancel from the east.

The porch and sacristy are covered with ceilings, the arms of the transept have cradle vaults, and the nave, cross bay and presbytery have apparent vaults resembling sails.

The façade consists of a two-storey tower with an octagonal cupola with a cross and annexes on its sides. The elevations of the upper storey of the tower are topped with triangular gables. The roofs of the church are covered with sheet metal; over the chancel and nave they are gabled, over the apse a multi-pitched roof, over the arms of the transept a triple-pitched roof and over the sacristy a double-pitched roof.

The forms of the church are neo-Gothic and the building itself is relatively simple. The monumental character of the church is given by the carefully worked stone blocks from which the church was built.

Painting decoration and furnishings
In the church we find the remains of a painting decoration, created during the First World War, by an anonymous artist, probably one of the Austrian soldiers stationed in the church. We find the "Dove of the Holy Spirit" on the chancel vault, floral representations on and geometric motifs on the ribs. We know the equipment of the church from the 1939 inventory. It was a wooden high altar with a painting of the 'Our Lady of Czestochowa', a wooden pulpit, ten unspecified paintings, as well as vestments and liturgical vessels. Today it remains lost.