V.O. Key, Jr., one of the country's foremost authorities on American government and politics, died yesterday morning after an illness of several months. Key, 55, was Jonathan Trumbull Professor of American History and Government.

"V.O. Key was probably the most distinguised political scientist in the country," said Robert G. McCloskey, professor of Government. Don K. Price, Jr., Dean of the Faculty of Public Administration, termed Key "the outstanding student of the functioning of parties and pressure groups."

Wrote Definitive Text

Valdimer Orlando Key's most famous book, Politics, Parties and Pressure Groups, has been the definitive text in the field for two decades. His Southern Politics in State and Nation, called a "truly major accomplishment" by McCloskey, received the 1949 Woodrow Wilson Award of the American Political Science Association. "It's kept on the book-shelves of every editor in Southern cities," said Price.

In his last work, a monumental study of Public Opinion and American Democracy published in 1961, Key synthesized all the findings made in his field and then added his own insights "much as Samuelson did in Economics," McCloskey noted.

Before joining the Harvard faculty in 1951, Key had served as head of the government departments at both Johns Hopkins and Yale. In 1958 he was President of the American Political Science Association.

Key, born in Austin, Texas, received his A.B. at the University of Texas in 1929. No matter where he traveled or what he did, "V.O. never lost his Texas upbringing and the salt and wit that goes with it," said Price. "To add this to his scholarship makes him a friend and colleague who will be deeply missed and never replaced."

Mr. Key is survived by his wife, Luella and three brothers and a sister in Texas. Memorial services will be held on Wednesday, October 9, at 2:30 p.m. in Memorial Church.