Lyricist Sir Tim Rice is spearheading an appeal to get Thame Players' development plan off the ground.
Sir Tim, a patron of Thame Players, is writing to local businesses to drum up cash for the last £100,000 of the £320,000 project.
Sir Tim, who wrote the lyrics for Jesus Christ Superstar, Joseph and his Amazing Technicolour Dreamcoat and The Lion King, used to live in Great Milton.
He said: "I have paid several visits to the Players' Theatre and always been impressed by the group's abilities.
"I am very happy to give them my full support in their new development plans.
"To give Thame a theatre of which it can be proud we need companies to help by making donations."
He said all donors would be permanently acknowledged in the new foyer while, for donations of at least £250, a seat would be dedicated in the company's name.
The Players Theatre in Nelson Street was once the church hall, but the players leased it and then bought it outright five years ago.
The Players were founded nearly 60 years ago.
Chairman Tony Long said the project is to provide a comfortable, modern and well equipped theatre, improved facilities for the disabled, more productions and a return of cinema to the town after 30 years.
There will be an improved auditorium, front of house area, better staging and a backstage area.
The group already has full planning permission for the development.
Thame Town Council and South Oxfordshire District Council have already awarded the project more than £160,000.
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