René Thomas was a Belgian-born guitarist who became one of the most sought-after players on the Paris modern-jazz scene. He was born in Liège on February 25, 1926, moved to Paris in the early 1950s, spent about five years in Montreal and New York, and from 1962 was again at the center of Parisian club and studio life, in Lou Bennett's organ trio, in a trio with Eddy Louiss and Kenny Clarke, and in Stan Getz's European quartet. He passed away in Santander, Spain, on January 3, 1975, at the age of 48.

He took up the guitar at about ten, taught by the companion of his sister, an Italian amateur guitarist, and was playing in orchestras around Liège by thirteen. In 1943 he recorded in Brussels with the accordionist Hubert Simplisse's dance orchestra. His first model was Django Reinhardt. After the war he played with the rising Belgian jazz musicians, above all the saxophonist and flutist Bobby Jaspar and the alto saxophonist Jacques Pelzer, and in the early 1950s he turned to bebop, cool jazz and the music of Lennie Tristano.

When his father died in 1952 he inherited the family's jute-sack factory, chose a musician's life over it and moved to Paris, where he played in the clubs. There Jimmy Gourley introduced him to the records of the American guitarist Jimmy Raney, and the mix of Raney's cool, linear phrasing and Reinhardt's attack became the basis of his own style. Between 1954 and 1956 he recorded as a leader for Vogue, Barclay and Polydor. His Vogue quintet record, René Thomas et son quintette, was recorded in Paris on May 5, 1954 with the pianist Henri Renaud and the trumpeter Buzz Gardner. His Barclay 10-inch LP, René Thomas and His Orchestra (1956), has the pianist René Urtreger and the tenor saxophonist André Ross, and a Polydor EP by his Modern Group was recorded in Paris on March 22, 1956. The New York Times obituary also places him with Chet Baker in Paris in 1955.

In April 1956 he moved to Montreal with his family and the drummer José Bourguignon, and stayed about five years as a key member of the city's jazz community. From Montreal he traveled often to New York to work with American players; French and Belgian biographers name Jackie McLean, Herbie Hancock and Wayne Shorter among them, and in 1958 he joined Sonny Rollins's group. In July 1958 he is the guitarist on the big-band side of Rollins's Sonny Rollins and the Big Brass (MetroJazz), recorded in New York with arrangements by Ernie Wilkins, and he also appears on Toshiko Akiyoshi's United Notions that year. In February 1960 he was playing at the Café Lutèce in Montreal, where live tapes were later made. His own Guitar Groove (Jazzland), made in New York on September 7 and 8, 1960, with the tenor saxophonist J. R. Monterose, the pianist Hod O'Brien, the bassist Teddy Kotick and the drummer Albert Heath, was produced by Orrin Keepnews and remains his best-known leader record.

He returned to Belgium with his family in 1961 and played the Comblain-la-Tour festival on July 30 that year; on November 6, 1961 a quartet of Thomas and Jaspar was taped at the Jazz aux Champs-Élysées concerts in Paris. He and Jaspar formed a short-lived International Jazz Quintet, and in Italy they made the Thomas-Jaspar Quintet record (RCA Victor), with Amedeo Tommasi on piano, and joined Chet Baker's sextet for Chet Is Back!, taped in Rome in 1962. A live set with Baker in Bologna on April 15, 1962 survives on a later release. When Jaspar's health failed in 1962, Thomas worked with Pelzer, and the organist Lou Bennett proposed a trio with Kenny Clarke on drums, an organ combo that became one of the leading groups in the Paris clubs. In 1963 he made Meeting Mister Thomas for Barclay (recorded on March 23 and April 20), played on Lou Bennett's Enfin ! (recorded in Paris that March) and on quintet tracks of the alto saxophonist Sonny Criss's Paris sessions of April and October 1963, and recorded Hoffmann's Hammond Tales for Philips with the German organist Ingfried Hoffmann (July 14, 1963). In October 1964 he was recorded at the Blue Note club in Paris with the saxophonist Pony Poindexter and the pianist Georges Arvanitas, a set that came out in 1990. In 1965, by his French biographers' account, he briefly joined Lee Konitz's group; he played with Henri Texier in the mid-1960s and made a quartet LP with Jack Diéval for Relax, issued in 1967.

Around 1966, despite warm reviews, he stepped back from the scene for a time. A producer brought him back in 1968 with a group of lesser-known players, and he recorded with Louiss on organ and Clarke on drums in the trio whose record came out on the small Cy label in 1973. In 1969 and 1970 he worked with Lucky Thompson (A Lucky Songbook in Europe, MPS) and J. R. Monterose, and in 1970 he was in Le Havre with Clarke and Louiss for a live set. Late in 1970 Stan Getz hired the Thomas-Louiss-Bernard Lubat trio for concerts across Europe, and Getz's double album Dynasty was taped with that quartet at Ronnie Scott's club in London on March 15, 16 and 17, 1971. In 1972 Thomas and Pelzer formed TPL (Thomas Pelzer Limited), whose modal-leaning album was recorded at Reward Studios in Schelle, Belgium, on February 26, 1974, with the drummer Han Bennink. Five days earlier, on February 21, 1974, a live set with a Dutch rhythm section had been taped at Laren in the Netherlands; it was issued by Timeless in 1994 as Hommage à ... René Thomas.

At the end of 1974 he left with Lou Bennett and the drummer Al Jones for a tour of Spain. He died of a heart attack in Santander on January 3, 1975, and is buried in the Robermont cemetery in Liège. Larry Coryell and John McLaughlin dedicated a piece to him on Coryell's Spaces, and Philip Catherine named a track on his 1975 album Guitars after him. The 1991 CD Guitar Genius, assembled at the request of his daughter Florence Thomas, carries sleeve tributes from Coryell, Catherine, Sacha Distel, Sonny Rollins, Stéphane Grappelli and Toots Thielemans.

AllMusic describes a cool-toned, much-in-demand guitarist of the 1950s who played in a style similar to Jimmy Raney's, and the French and Belgian accounts add Django Reinhardt as his first model and Raney, whose records Jimmy Gourley showed him in Paris, as the second. He played a Gibson ES-150 (the Charlie Christian model), then an ES-175D, and went back to the ES-150. The combination gave him a linear, unhurried bebop line that could still dig into blues and hard-bop material, as Guitar Groove shows with J. R. Monterose on "Milestones" and "Ruby, My Dear", and his years in organ trios with Lou Bennett and Eddy Louiss added a more blues-based edge. He was little known to the wider public but admired by other guitarists: Franco Cerri named him among his main influences, and Belgian sources hear his influence in the playing of Larry Coryell, John McLaughlin and Philip Catherine. Much of his recorded legacy was issued after his death, from the 1990 Blue Note club recording to the 1991 and 1992 Guitar Genius CDs of live tapes and the 2020 Fresh Sound anthology Remembering René Thomas.