James V. Bennett, 84, a former director of the U.S. Bureau of Prisons and a prison reformer of wide renown, died of kidney failure Sunday at Suburban Hospital in Bethesda.

Mr. Bennett's career in the U.S. government began in 1919, when he was hired as an $800-a-year clerk in the old Bureau of Efficiency, a fore-runner of the Bureau of the Budget and the Office of Management and Budget. Ten years later he wrote a report for Congress that led to legislation establishing the Bureau of Prisons. In 1930, he was named assistant director of the new bureau and in 1937 he became its director, a position be held until his retirement in 1964.

The reforms he instituted over the years now are commonplace, But they were virtually unknown in the United States when he began his work. They range from the provision of job training for inmates to halfway houses - facilities in communities where prisoners nearing the end of their terms can begin to get the "feel" of leading normal lives.

All of Mr. Bennett's work was channeled towards the rehabilitation of prisoners rather than the mere punishment of them. "The four horsemen of penology are disease, overcrowding, idleness, despair," he said in an interview in 1937. "I don't know which of these is most destructive. But I believe nothing can have so denigrating an influence upon the human being as despair."

"Society need have no concern about our prisons being made so attractive to the men they will want to return. Imprisonment, being shut out from life, is punishment enough. Our job is to return that man to society better fitted to adjust himself to it and with an attitude of mind that will not stand in the way of that adjustment."

Mr. Bennett frequently was accused of "coddling" prisoners during his career and he denied it. He emphasized that the function of the bureau was to carry out the sentences of the courts - but he always maintained that prisoners must be given a chance to reform.

The notion of rehabilitation scarcely existed in the federal penal system when Mr. Bennett began his work with it. In 1926, he was assigned to help conduct an investigation into the three federal penitentiaries that existed at the time: Atlanta, Ga., Leavenworth, Kan., and McNeil Island, Wash.

The wardens of each of the institutions were appointed by the President.The guards and other custodial personnel were recruited through political patronage systems with little or no regard for their qualifications. Some prisoners received favored treatment and there were other irregularities.

Accoridng to Norman A. Carlosn, the present director of the bureau, prisoners at that time were chained together to move in a lock-step, they ate out of bucklets, and they lived in dormitories or large cells where the stronger inmates frequently abused the weaker ones. There was little to do, no prison industries having yet established. Counselling and educational services were limited to what a chaplain could provide.

The study that Mr. Bennett began making in 1926 concluded with the report he wrote for Congress in 1929 and the establishment of the Bureau of Prisons in the following year.

Sanford Bates was the bureau's first director. He and Mr. Bennett began reforming the system. Stripped suits and numbers were among the first symbols of the old ways that were abolished. In 1933, Mr. Bennett was named head of the new federal prison industries program.

In 1938, a year after he succeeded Bates as director, Mr. Bennett established the nation's first open prison at Seagoville, Texas. It had no walls or bars and the guards went unarmed.

Causes for which Mr. Bennett fought over the years included "indeterminate" sentences - sentences that would allow corrections personnel to release prisoners were ready for it. Mr. Bennett opposed the fixing of minimum penalties for most crimes for this reason.

He also believed that ties between prisoners and their families and communities should be preserved as much as possible. He liberalized mail and visiting privileges at federal facilities. He also opposed persistent efforts to have the D.C. Correctional complex at Lorton, Va., turned over to the federal government.

Following his retirement, Mr. Bennett continued to press for prison reforms. He also was a frequent and outspoken advocate of strict gun-control laws.

In 1968, he was a member of the Maryland Constitutional Convention which rewrote the state's constitution. He also served for many years as chairman of the American Bar Association's section on criminal law. He was delegate to ABA conferences in London in 1957 and 1971. He represented the United States at a United Nations conference on crime in 1970 held in Japan. He was a member of the Cosmos Club.

Mr. Bennett was born in Silver Creek, N.Y. He was an aviation cadet during World War I and then graduated from Brown University. After moving to Washington in 1919, he attended night law classes and earned his law degree from George Washington University in 1926.

In 1971, he published a book, "I Chose Prison."

Mr. Bennett's first wife, the former Marie Ettl. whom he married in 1919, died in 1967.

Survivors include his second wife, the former Olympia Stone, whom he married in 1971, of the homes in Bethesda and Boca Raton, Fla.; three children by his first marriage, Edmund Bennett, Ann Humbret and Brenda Bell, all of Bethesda; two brothers, Edmund and Kingsley Bennett, and two sisters, Wilhelmina Cox and Dorothy Vaughn, all of North Providence, R.I., and ten grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the James V. Bennett Memorial Scholarship Fund for Offenders, c/o Century National Bank, 5454 Wisconsin Ave., Chevy Chase, Md. 20015.