Baroness Jeanne de Rothschild, an actress whose much-publicized romances with famous figures culminated in her marriage in 1952 to a scion of the Viennese branch of the Rothschilds, died on Feb. 12 in her home in Monte Carlo. She was 94.

She was born Ivy Sweet, the daughter of a laborer, in Hampstead in north London, on Aug. 13, 1908. Under the stage name Jeanne Stewart, she appeared on the London and New York stages and in films made from 1931 to 1939.

One of her movie roles was as a seductress in the 1936 Zoltan Korda film "Forget Me Not." Another was as a mistress who was killed in "The Great Defender," made in 1934 by Thomas Bentley.

The popular press avidly reported her romances, real and imagined. In 1934, she married the industrialist Bernard Dudley Docker. Mr. Docker's father was so upset that he hired private detectives to track his son's new wife. The son divorced her after discovering her with the actor David Hutcheson.

After the five-month marriage, Miss Stuart returned to the stage, and for three years her name was linked romantically to the actor James Stewart and to the Earl of Carnarvon, according to an obituary in The Daily Telegraph.

After World War II, she settled on Long Island, where she was introduced to Baron Eugene de Rothschild, then living in Locust Valley in reduced circumstances. The Austrian Rothschilds, whose property had been confiscated by the Nazis, had moved to the United States after most of Central Europe fell under Soviet rule, limiting opportunities for private bankers.

The baron had first pursued a military career, but after its defeat in World War I, Austria was effectively disarmed. He devoted himself to intellectual pursuits, which included writing a manuscript on Titian and correcting Einstein on an error the baron discerned in Einstein's logic. Einstein thanked him and said the mistake occurred because of a typographical error, according to "The Rothschilds: A Family of Fortune" by Virginia Cowles.

In 1925, the baron married Kitty Schoborn-Bucheim, a divorced American woman, of whom his family and their circle disapproved, according to "Rothschild: The Wealth and Power of a Dynasty" by Derek Wilson. She died in 1946.

In 1952, when the baron was 64, he married Miss Stuart, who was 24 years his junior. By all accounts, it was a happy union, and the beauty of her youth persisted into old age. She also helped him in legal efforts to recoup his fortune.

In the late 1950's, they settled in Monte Carlo, where they became friends of Prince Rainier and Princess Grace. The baron died in 1976. The baroness left no immediate survivors. She was a cousin-in-law of Baroness Liliane de Rothschild, who died on Feb. 17.