Born in Budapest, in 1905, to an impoverished Hungarian mother and Czech father, Kraus entered the Academy of Music there as a piano major at age 8. Taught by Kodály and Bartók, among others, she graduated in 1922, with top honors. Kraus then attended the Vienna Konservatorium to study with Eduard Steuermann and Schnabel, from whom she took master classes. Starting in 1925, became a teacher there herself for six years. In the 1930s, she toured both as soloist and as the recital partner of violinist Szymon Goldberg, with whom she recorded Beethoven and Mozart sonatas for British Parlophone in 1935 and 1937, along with solo reperoire. Her other specialties included Chopin, Haydn, Schubert, and Bartók.
When Kraus married philosopher Otto Mandl, they converted to Catholicism, living in Italy until the cloud of Nazism compelled them to move to the Dutch East Indies. While touring in 1942, Kraus, her husband, and their two children were arrested in Indonesia, and sent to separate prisoner-of-war camps on Java for nearly three years. They survived principally because the Japanese knew her name and her recordings. A Japanese conductor reputedly provided food as well as musical scores until their rescue by British forces. For two years Kraus played in Australia and New Zealand (where she became a British subject), and in South Africa too, before returning to England in 1948, where she resumed her career before debuting in the U.S., in 1949. She also resumed recording, albeit with second-class Viennese orchestras and conductors for Vox, mainly, in concertos by Mozart and Beethoven, but later on for Vanguard in the U.S. During the 1966-1967 season, she performed 25 of Mozart's 27 concertos in New York City on a single series, and the next season played his complete keyboard sonatas.
A nonstop talker who designed her own concert gowns, Kraus was never ranked as a virtuoso even before World War II, but she was a notably distinguished interpreter. Those who heard her before and after the war confided sadly that something had forever changed. She never stopped playing, however -- always forthrightly, even brusquely, in some repertoire. Texas Christian University at Fort Worth appointed her artist-in-residence in 1968, and she became a regular juror at the Cliburn International Competitions. She tried to instill in her pupils the same enthusiasm that sustained her as a public concert artist until 1982, an intensity that unnerved some of the shy and introverted students. At various U.S. piano competitions, regular observers labeled her a surrogate stage-mother, as she endlessly exhorted and lobbied. But she taught and cherished her pupils, emulating the teachers from her childhood.
In 1978, the Austrian government awarded Kraus the Cross of Honor for Science and Art. Remaining a British subject, she taught in Texas until her retirement in 1983. She maintained a home in Asheville, North Carolina, where she died in 1986.