Pope Benedict XVI was scheduled to hold the open-air mass at Coventry Airport, but the service will instead take place at Cofton Park in Birmingham, which has a capacity of up to 80,000.
It is thought that the airport site could hold around 150,000, but a Catholic Church spokesman said the new venue had been selected because of its "historical resonance" and close association with Cardinal John Henry Newman, the revered 19th century clergyman and Catholic convert who will be beatified on the final day of the papal visit later this year.
Alexander des Forges, spokesman for the Catholic Church, said: "As a Church we have asked Birmingham City Council for Cofton Park to be the venue for the beatification of Cardinal Newman on September 19, the last day of the Pope's visit.
"I cannot comment at all on Coventry, but I can say that a significant number of pilgrims will be able to attend the beatification at Cofton Park.
"The point to make is that, whichever way you cut it, when it comes to the capacity we are looking at a very significant number of people will be able to attend."
The spokesman said organisers were expecting around 80,000 pilgrims to attend the Birmingham service.
He added: "With Cofton Park you have a very close association with Cardinal Newman because it is immediately adjacent to Oratory House in Rednal, where Cardinal Newman found a place of retreat for quiet reflection.
"And most particularly, he is buried in Rednal Cemetery.
"Choosing Cofton Park as a venue for the beatification will also enable the Pope to pay a private pilgrimage to the rooms of Cardinal Newman at Birmingham Oratory."
SIC: UKPA