George H. Mahon, a Texas Democrat who presided over many of the nation's great defense spending debates during 14 years as chairman of the powerful House Appropriations Committee, died yesterday at a hospital in San Angelo, Tex., after an apparent heart attack. He was 85.

The son of a poor cotton farmer, Mr. Mahon represented the 19th congressional district near Abilene for 44 years before retiring in 1978. He was widely respected by members of both parties for his even temperament and judicious spending policies.

In recent years, Mr. Mahon had suffered increasingly from severe arthritis and Parkinson's Disease. He underwent surgery last week near his home in Loraine to have an artificial joint implanted in his knee.

He was one of nine children and picked cotton as a boy, but he worked his way through college and law school and became the local county attorney and district attorney for the 32nd judicial district in Texas.

With West Texas locked in the grip of the Great Depression, Mr. Mahon was elected the first representative from the newly created 19th district in 1934. He identified strongly with the Roosevelt administration's New Deal, which was then promising to bring electricity for the first time to some impoverished areas of the state.

Another Texan who came from a similar background -- and was a lowly Hill staffer when Mr. Mahon arrived in Washington -- would rise faster and higher in the political hierarchy. But while Lyndon Johnson was maneuvering to become party leader, Mr. Mahon was building a reputation for steadfastness unmarked by great personal ambition.

His selection as chairman of the Appropriations Committee in 1964 made him one of the most powerful members of the House. Still, he shunned the trappings of power and walked the halls of Congress a virtual portrait of the rough-hewn Texas traditionalist.

A devout and abstemious Methodist, he preferred playing golf to the politics of running for office and could sometimes be heard singing hymns while walking the fairways. He rented an apartment while in Washington, believing that a house purchase would be too pretentious.

In the 1970s, Mr. Mahon locked horns with Pentagon officials over the best use of defense funds. He played a leading role in votes leading to compromise on B1 bomber spending and staunchly resisted efforts by liberal Democrats to make public the size of the budgets of intelligence agencies, including the Central Intelligence Agency.

When he left Washington, Mr. Mahon returned to his home in Loraine, where he spent most of his time organizing his personal papers and overseeing the cotton crop on a 400-acre farm he owned nearby.

Survivors include his wife, Helen; a daughter, Daphne Mahon Holt, and three grandchildren.