Karl Boehm, 86, one of the most important conductors of the generation that succeeded Arturo Toscanini and Bruno Walter, died yesterday in a hospital in Salzburg, Austria.

Mr. Boehm had been ill since suffering a stroke in Vienna last March during a television recording of "Elektra," by his mentor Richard Strauss.

Mr. Boehm's condition deteriorated earlier this week and doctors said two days ago that he had lapsed into a coma at his Salzburg home.

The illness had forced Mr. Boehm to cancel most of his plans to conduct this summer. But he still planned to direct one concert at the Salzburg festival, the Associated Press reported.

Mr. Boehm, the only person ever titled Austria's general music director, developed a world-wide reputation during more than 60 years of music making. He served two tenures as director of the Vienna State Opera (1942-1945 and 1954-1956). And as a result of his closeness to Richard Strauss he conducted the premieres of two Strauss operas, "Die Schweigsame Frau" and "Daphne," the latter being dedicated to him. He conducted the reopening of the rebuilt Vienna Opera in 1955 with Beethoven's "Fidelio."

Mr. Boehm's period of great renown in the United States came late, when he became the mainstay of the German repertory at the Metropolitan Opera after his debut in 1957 with "Don Giovanni." He was specialist in Wagner, Mozart, Beethoven and Richard Strauss there in the ensuing two decades.

His most important appearances in Washington came even later, when he directed Mozart's "Cosi Fan Tutti" at the Kennedy Center with Berlin's Deutsche Oper in 1975 and Mozart's "The Marriage of Figaro" and Strauss' "Ariadne auf Naxos" with the Vienna Opera there in the fall of 1979. It was during that last visit that Mr. Boehm led the Vienna Philharmonic in an enchanting encore performance of Johann Strauss Jr.'s "To the Beautiful Blue Danube" that many regard as one of the finest moments yet in the center's musical history.

Mr. Boehm was a member of that Central European generation of conductors that included George Szell, Fritz Reiner, Otto Klemperer and Eugene Ormandy. A leading member of the succeeding generation, Erich Leinsdorf, declared yesterday, "One of the important links with the past is gone." Former Met general manager Sir Rudolf Bing, who hired Mr. Boehm for that company, said, "I think there is little doubt that he was one of the few great conductors still around."

Grove's Dictionary of Music and Musicians aptly describes Mr. Boehm's style as "expressed in strictly functional gestures" and "direct, fresh, energetic and authoritative, avoiding touches of romantic sentimentality or self-indulgent virtuoso mannerisms. His skillful balance and blend of sound, his feeling, his feeling for a stable tempo and his sense of dramatic tension make Mr. Boehm one of the outstanding conductors of the century."

Of the major conductors of his time, perhaps only Leopold Stokowski continued regular conducting later in life.

Few conductors have more extensively documented their work on recordings. While no precise figures were available yesterday, there was agreement that Mr. Boehm was roughly in the class of Ormandy, Bernstein and Von Karajan in the size of his recorded legacy. Further, there are outstanding video versions of works like Mozart's "The Marriage of Figaro" and his Requiem that have been widely shown in this country on PBS.

Mr. Boehm, the son of a lawyer and a pianist, was born in Graz, Austria, on Aug. 28, 1894. He studied law, taking a doctorate from Graz University in 1919. Also, he studied music with private teachers in Graz and then from 1913 to 1914 with Eusebius Mandyczewski and Guido Adler in Vienna. Then he returned home, coaching singers at the Graz Opera, making his debut as a conductor in Nessler's "Der Trompeter von Sackingen" in 1917.

Carl Muck and Bruno Walter, who invited Mr. Boehm to the Munich State Opera in 1921, were principal influences on his style.

He left Munich after six years and in 1927 became music director at Darmstadt, which is where Bing got to know him. There he performed many modern operas, including Alban Berg's "Wozzeck." Along with the later "Lulu," Mr. Boehm was the person who introduced these operas to many cities. Mr. Boehm moved to Hamburg in 1931.

It was in 1933 that Mr. Boehm started his long and close association with the Vienna Philharmonic in concert and opera performances. By the time the opera and the philharmonic visited here almost two years ago his relationship with those musicians seemed almost telepathic. By then he conducted mostly from a chair, and the gestures were minimal. For long periods he would not even beat time, but the musicians had so close a bond that they seemed to know what Mr. Boehm wanted. While they respected the other conductors on the visit, Leonard Bernstein and Zubin Mehta, they made it clear that it was Mr. Boehm they admired the most. They told of their 85th anniversary gift to him, an exercise rug which he got out each morning at his suite in the Watergate to do his calisthenics.

Mr. Boehm accepted an invitation to be the director of the Dresden State Opera in 1934, and remained there for nine years, in what was regarded as one of the company's finest periods. It was then that he became close to Richard Strauss.

During World War II, he moved on to Vienna. Several years ago, he rejected allegations of past Nazi connections that were raised in several Vienna papers, claiming that he had been seen wearing a swastika. He replied heatedly, "I have never been a Nazi. Nobody could have seen me wearing the swastika emblem."

During the postwar period he conducted frequently around the world.

One place that particularly caught his fancy was the Kennedy Center Opera House. In 1975 he told The Post's critic, Paul Hume, that "it has the most magnificent acoustics in the world except for the Musikvereinsaal in Vienna."

Mr. Boehm is survived by his wife of 54 years, Thea, and his son, actor Karl-Heinz Boehm.