Rotherwas Chapel, in Herefordshire, has been unused for many years and currently can only be viewed by making an appointment through English Heritage.
But a newly formed Friends of the Chapel group are striving to make the historic chapel, once part of a large estate, more accessible to visitors.
The mass, open to all, is due to take place on Monday.
Margot Miller, a member of the Friends of the Chapel, which formed earlier this year, said research had not thrown up any records of mass ever being held there.
"It was originally used as a family church for the Bodenham family, not a parish church, so we don't know if any mass was heard," she said.
The Ministry of Defence took over the building after the death of the last Bodenham family member and it was used by soldiers defending the munitions factory in Rotherwas.
The rest of the estate was knocked down.
English Heritage eventually took the chapel over and Ms Miller and other volunteers formed a group to help look after and clean the building.
"It is a lovely chapel," she said.
"A beautiful little building. We think it was mainly used in the 16th century and it has a little altar and stained glass windows. The Bodenham family spent a lot of money on it."
The first mass is designed to coincide with celebrations for the Feast of the Assumption. The chapel is called Our Lady of the Assumption.
Plans for a memorial for Henry Bodehnam, killed in France in 1916, are being arranged for September and it is also hoped a carol service will be held in December.
A little-used chapel is to host what is thought to be its first public mass.