LOS ANGELES, DEC. 10 -- Armand Hammer, a socialist's son who became a titan of American capitalism and a tireless crusader for such causes as world peace and curing cancer, died tonight at 92. The cause of death was not announced.

Hammer died at his home after a brief illness, according to a spokesman for Occidental Petroleum Corp., the giant oil company of which Hammer was chairman.

The affable Hammer was a self-made millionaire by the time he graduated from Columbia University medical school at age 23. During a lifetime of international wheeling and dealing, he came to know -- sometimes on a first-name basis -- world leaders from Vladimir Lenin to Ronald Reagan.

His empire rested upon Los Angeles-based Occidental. He bought the tottering company for $100,000 in 1957, then turned it into the nation's seventh-largest oil company, valued at $20 billion.

Hammer's death came the night before he was to celebrate his bar mitzvah, 79 years late, at a star-studded ceremony and fund-raiser.

From his earliest days of dealing with the fledgling Soviet Union, Hammer was in the forefront of negotiating huge deals with communist countries to develop their untapped natural resources.

Hammer said he had two dreams: a cure for cancer and peace between East and West. After the Chernobyl nuclear accident in the Soviet Union, he arranged visits by U.S. specialists in bone-marrow transplants, an important technique for saving lives of radiation victims.

Hammer was born in 1898 in a cold-water flat in New York City's Lower East Side. His great-grandfather built warships for Czar Nicholas I; his Russian-born father was a doctor and a founder of the American Socialist Party.

After serving in the U.S. Army Medical Corps in World War I, Hammer went to medical school at night and worked during the day to bail out the family's small, nearly bankrupt pharmaceutical firm. He never did practice medicine, but he managed to turn the company into a million-dollar enterprise.

After the Bolshevik revolution of 1917, he worked out a deal to trade U.S. grain for Soviet products.

Hammer became a hero in the Soviet Union. Lenin granted him a license as the sole representative of 38 leading American manufacturers.

Hammer was married three times. His third wife, Frances, died in 1989.