Paul H. O’Neill had just presided over a celebrated revival of the aluminum giant Alcoa and was about to begin his retirement in late 2000 with a long drive across the back roads of America in a new Bentley Flying Spur.

Then came calls from Vice President-elect Dick Cheney asking him to become secretary of the Treasury. Despite having a list of reasons for being not right for the job — a key one was that he had grown used to being the boss — Mr. O’Neill agreed.

It turned out to be an agonizing tenure.

Mr. O’Neill lasted less than two years in the job; his outspoken independence was seen as political disloyalty, and President George W. Bush fired him in December 2002.

On Saturday, Mr. O’Neill died at his home in Pittsburgh at 84. His son, Paul Jr., said the cause was lung cancer.