Eugene McDuffy, who performed as "Brother" Jack McDuff, was born September 17, 1926, in Champaign, Illinois. He started as a bassist, playing in Joe Farrell's group, before Willis Jackson, in whose band he also played bass in the late 1950s, encouraged him to switch to organ. He moved to the instrument, caught Prestige Records' attention while still with Jackson's group, and made his debut as a leader with Brother Jack for the label in 1960, the first in a run of classic soul-jazz releases through the era's hard bop peak.

McDuff soon became a bandleader in his own right, hiring a young guitarist named George Benson to add "class and fire" to several of his albums; George Benson's own career is covered in full in his JazzProfiles.com profile. McDuff went further than most bandleaders would for a sideman: he set up Benson's own first recording as a leader, using McDuff's own group for the session. Beyond Benson, his bands featured saxophonist Red Holloway and drummer Joe Dukes, and his classic Prestige-era catalog includes The Honeydripper (1961), with tenor saxophonist Jimmy Forrest and guitarist Grant Green, and Brother Jack Meets the Boss (1962), featuring Gene Ammons.

McDuff, later known as "Captain" Jack McDuff, died of heart failure in Minneapolis, Minnesota, on January 23, 2001, at age 74.

McDuff's organ-trio format, built around soulful, blues-inflected grooves in the tradition of Jimmy Smith, became a launching pad for other musicians' careers as much as a vehicle for his own playing, most notably George Benson's.