The venerable composer and lyricist visited the Stephen Colbert show, where he discussed cooking up new shows, even as he continues into his 90s.
Sondheim said: "I'm been working on a show with a playwright named David Ives called "Square One", and we had a reading of it last week that was really encouraging, so we're going to go ahead with it, and with any luck, we'll get it on next season."
Reports have stated that Broadway legends Nathan Lane and Bernadette Peter were involved in the reading, though it is unclear if the pair will be involved in the full production.
Ives' previous work has included working on the book for the Broadway version of the musical Dance of the Vampires. Ives and Sondheim had previously been working on a now-cancelled show based on two films by Luis Buñuel – though it is unconfirmed if this, in fact, has been revivified as "Square One".
Sondheim who has a few busy months coming up: the new revival of his lauded musical Company is set to open later this year on Broadway, following its award-winning West End production.
The Follies creator also teased a "few real surprises" in Steven Spielberg's new version of West Side Story (a musical that he created the original lyrics for), which released a new trailer yesterday, especially in "the way the songs are used."
Hopefully, it won't be too long before the show heads to the UK.
Watch Sondheim's interview with Colbert here: