Dave Brubeck, a jazz pianist who had unparalleled commercial success, expanding musical boundaries with his compositions and carrying jazz throughout the world on U.S. State Department tours, died Wednesday at a hospital in Norwalk, Conn., one day before his 92d birthday.

His manager, Russell Gloyd, said Mr. Brubeck was on his way to a regular medical checkup when his heart gave out.

Over a seven-decade career, Mr. Brubeck wrote hundreds of tunes, including the oft-recorded "In Your Own Sweet Way" and "The Duke." His quartet, featuring alto saxophonist Paul Desmond, was one of the most popular jazz groups in history and in 1959 recorded the million-selling instrumental hit "Take Five."

Mr. Brubeck composed ambitious classical and choral works, released nearly 100 albums, and remained a charismatic and indefatigable performer into old age.

A bespectacled cowboy who grew up on a remote California ranch, Mr. Brubeck was known for his complex rhythmic patterns, which he said were inspired by riding his horse and listening to its syncopated hoofbeats striking the ground.

He studied in the 1940s with the experimental French composer Darius Milhaud, who encouraged his interest in jazz. Mr. Brubeck was among the first jazz musicians to make wide use of polytonality, or playing in more than one key at a time. He was also an early advocate of "world music," adopting exotic sounds that he heard in his worldwide travels.

After forming his quartet in California in the early 1950s, Mr. Brubeck branched out from nightclubs to begin playing on college campuses, which produced a nationwide sensation with record sales to match. "We reached them musically," he told the New York Times in 1967. "All we presented was music."

With their curly hair and horn-rimmed glasses, Desmond and Mr. Brubeck looked like professorial brothers, and were unlikely jazz stars. They could anticipate each other's bandstand improvisations, as Desmond's ethereal, upper-register saxophone soared above Mr. Brubeck's driving keyboard attack.

With the release of "Time Out" in 1959, Mr. Brubeck had the first jazz album to sell more than one million copies. It reached No. 2 on the pop charts, and its eternally catchy signature tune, "Take Five," became a surprise hit.

"Take Five" became a staple of Mr. Brubeck's concerts and helped make the Dave Brubeck Quartet the most popular jazz group of the 1950s and '60s.

Mr. Brubeck defied the raffish image of the jazz musician by being a clean-living family man who lived with his wife and six children. He was considered a seminal force in the West Coast's understated "Cool Jazz" school of the 1950s, but he disdained the label and preferred to forge an original musical path.

After early struggles, Mr. Brubeck was reportedly earning more than $100,000 a year by 1954, the year he became the second jazz musician to be featured on the cover of Time (after Louis Armstrong in 1949).

Some musicians and critics openly resented his success, and others questioned his prominence in a form of music that was created primarily by black musicians.

But Mr. Brubeck was an outspoken advocate of racial harmony and often used his music as a platform for cross-cultural understanding. He once canceled 23 of 25 concerts in the South when local officials would not allow his African American bass player, Eugene Wright, to appear with the group.

In 1958, Mr. Brubeck and his quartet undertook an arduous international tour for the State Department, spreading the improvisatory spirit of jazz to Iran, Iraq, Afghanistan, Pakistan, Turkey, and Sri Lanka, among other countries. In Poland, they were among the first U.S. jazz musicians to perform behind the Iron Curtain.

David Warren Brubeck was born on Dec. 6, 1920, in Concord, Calif. He and his family lived on a 45,000-acre ranch near Ione.

His father was a champion rodeo roper and his mother was a conservatory-trained pianist who had studied in London with concert star Dame Myra Hess. She gave her three sons a surprisingly advanced musical education, and Mr. Brubeck's two older brothers, Henry and Howard, became music teachers and composers.

Because of early eyesight problems, Mr. Brubeck always had difficulty reading musical notation. He compensated by learning to improvise and play by ear, which served him well in jazz.

At the University of the Pacific in Stockton, Calif., Mr. Brubeck proposed on his first date with Iola Whitlock, and the two were married in 1942. She sometimes wrote lyrics for his music and managed their growing household.

During World War II, Mr. Brubeck was pulled from the infantry ranks to start a jazz band to entertain troops on the front lines. The group was perhaps the only integrated musical unit in the military during the war.

When Mr. Brubeck received a Kennedy Center award in 2009, President Obama said, "You can't understand America without understanding jazz, and you can't understand jazz without understanding Dave Brubeck."