Mike Wilson and Richard Hand, two University of Glamorgan professors, found the short play in archives in the British Library while they were researching a book they were writing about the London-based Grand Guignol troupe, which performed the play in the 1920s.
The work has never been published, and the professors said the Noel Coward estate believes this copy to be the only one in existence.
The comedy of manners focuses on a husband and wife. Prof. Wilson told BBC, "The husband and wife are in an unhappy relationship and he is about to embark on an affair, but he is an honorable man and refuses to consummate it. They are trying to keep it away from the wife but unknown to him, she already knows and is trying to encourage it because she knows they are unhappy. It's quite unconventional."
A London theatre company called The Sticking Place plans to perform the play in November.
Coward (1899-1973) was a poet, actor, screenwriter, playwright, composer and lyricist known for Private Lives, Design for Living, Sail Away, Blithe Spirit, Cavalcade, Tonight at 8:30 and many other works for the stage.