Roy Kral and Jackie Cain in an undated photo.

Jackie Cain, the sparkling jazz singer who teamed with her husband, Roy Kral, and became an acclaimed act on record and stage for more than a half-century, died Sept. 15 at her home in Montclair, N.J. She was 86.

The cause was complications from a stroke about four years ago, said the music writer James Gavin, a family friend.

Jackie and Roy, as they were known, rose to initial prominence as singers — she an effervescent soprano, he a warm baritone — with the bebop saxophonist Charlie Ventura and his “Bop for the People” band in the late 1940s.

With such songs as “East of Suez” and an uptempo version of the pre-Jazz Age warhorse “I’m Forever Blowing Bubbles,” Jackie and Roy were among the first to shape the art of vocalese, a wordless singing style modeled on intricate bebop harmonies and phrasing.

Vocalese was further popularized by King Pleasure, the vocal trio Lambert, Hendricks and Ross, the group Les Double Six and, in later years, the Manhattan Transfer.

At their commercial peak, Jackie and Roy found champions at major record labels such as Columbia, ABC-Paramount, Verve and Atlantic. Their style was crisp yet harmonically daring, cool but emotionally sophisticated, usually aided by a first-rate backup combo with Kral on piano. They worked with top-flight arrangers such as Quincy Jones, Ralph Burns and Bill Holman.

Among their staples were “Mountain Greenery,” “Spring Can Really Hang You Up the Most” (one of the first recordings of the Fran Landesman-Tommy Wolf standard), “The Glory of Love,” “You Inspire Me” and “Cheerful Little Earful.”

In addition to pulling from the Great American Songbook of the Gershwins, Rodgers and Hart, and Cole Porter, they stretched into Brazilian bossa nova, Broadway show tunes, cabaret music, and contemporaneous composers such as Alec Wilder and André and Dory Previn.

Jackie and Roy worked extensively at jazz festivals, in concert venues from Las Vegas to Johannesburg, and at supper clubs in New York, Washington, Los Angeles and other major cities.

“They were a connoisseur’s delight,” said Gavin, who has written liner notes for their albums. “Jackie had an extraordinarily pure and accurate instrument. She was a great ballad singer, with a beautiful liquid sound, and a technical marvel.”

As they adapted to a musical era dominated by rock, they “went electric” at times and included material from the Beatles and Simon and Garfunkel. They also did prolific commercial jingle singing for shampoos, breakfast cereals and cars, among other products — lucrative but unsatisfying work they gradually stopped to refocus on jazz, Ms. Cain said.

Their concerts and recordings were remarkably consistent over the years, usually drawing praise from music critics for their delicate artistry, energetic professionalism and deeply felt onstage intimacy. They had, after all, been married as well as performing and honing their act since the Truman administration.

“I’m always a little nervous,” Ms. Cain told the Chicago Sun-Times in 1997. “I’m kind of a shy person who has always had to feel out a room before I feel comfortable and work up a sense of ease. But I’m more confident now. I talk to myself and say, you’ve been doing this for 50 years, so get over it!”

Jacqueline Ruth Cain was born in Milwaukee on May 22, 1928. Her father, a furniture salesman who also managed a community theater, presented her at an amateur hour show when she was about 6.

“I guess I liked that applause and attention,” she once told an interviewer. She proceeded to model her singing style on Jo Stafford, a jazz vocalist of impeccable tone and swinging rhythm.

At 14, Jackie summoned the courage to ask the visiting bandleader Horace Heidt if she could sing with his group. “I got up and sang one time and they asked me to come back and sing at every show,” she told jazz historian Gene Lees. “They put me on a chair, because I was very small.”

Within a few years, she began singing professionally in Chicago. One night, a friend invited her to sit in with a quartet at a Windy City club. The band’s pianist, Kral, did not think much of “girl singers” warbling to bebop music.

He then had a drink with Ms. Cain, and he warmed to the idea. “She was a voluptuous blonde, right out of high school,” Kral told the Chicago Sun-Times years later. “She was very convincing.”

The jazz-loving radio host Dave Garroway, later anchor of NBC’s “Today” show, became a promoter of the duo, and Ms. Cain and Kral found frequent work at Chicago-area clubs before landing their breakthrough job with Ventura.

They married in 1949 and continued performing together until Kral’s death in 2002. (His sister, the admired jazz singer Irene Kral, died in 1978.)

Survivors include a daughter, Dana Kral of Montclair; and two stepdaughters, Carol May of Elgin, Ill., and actress Tiffany Bolling-Casares of Los Angeles. Another daughter, Nicoli Kral, known as Niki, died in a car accident in 1973.

When the jazz critic Leonard Feather asked in 1986 how Jackie and Roy kept looking and sounding so youthful after years of rigorous touring, Ms. Cain quipped, “I guess our fans are getting older and their eyesight isn’t so good. That would explain how they think we look.”