His father was a ragtime pianist and his grandfather a Wagner critic. He was a student of Paul Hindemith at Yale University, before entering the U.S. Navy in 1942 where he served during World War II. After the war, he pursued a career on Wall Street and later, as a jazz pianist, after Duke Ellington heard him play the piano, and arranged an engagement for him at a New York jazz club.
From 1959 to 1961, he studied composition in Florence with David Diamond. Diamond encouraged him to incorporate his jazz sensitivities into his symphonic compositions. In December 1961, his first opera, Fortuna, premiered in New York City. In 1964 Eugene Ormandy and the Philadelphia Orchestra premiered his Elegy for Orchestra. In 1968, he was inducted into the American Academy and Institute of Arts and Letters. Thorne spent much of his career championing the works of emerging composers. He served as director of the Walter W. Naumburg Foundation and the Thorne Music Foundation from 1965–1974, organizations which commission new works by young composers. In 1977, he founded the American Composers Orchestra with Dennis Russell Davies. The orchestra focuses on performing new compositions by American composers.
Many of his over 100 compositions are characterized by a distinct jazz flavor. He is also one of the first classical composers to write for the electric guitar and electric bass guitar (Sonar plexus, 1968; Liebesrock, 1968–69). A discussion of his works appears in R. Tomaro: Contemporary Compositional Techniques for the Electric Guitar in United States Concert Music.
- 1995 Rome Prize
- Tomaro, Robert. 1992. The New Grove Dictionary of Opera, 4 vols., edited by Stanley Sadie. London: Macmillan Press; New York: Grove's Dictionaries of Music, Inc. ISBN 0-333-73432-7 and ISBN 1-56159-228-5
- Tomaro, Robert. 2001. "Thorne, Francis". The New Grove Dictionary of Music and Musicians, second edition, 29 vols., edited by Stanley Sadie and John Tyrrell, 25:[page needed]. London: Macmillan; New York: Grove's Dictionaries. ISBN 1-56159-239-0 and ISBN 0-333-60800-3