Lorraine Rowan Cooper, 79, a personality of intelligence and warmth who graced the Washington political and social scene with notable style and wit, died Feb. 3 at the Wisconsin Avenue Nursing Home. She had suffered a stroke some months ago.

On March 17, 1955, the former Lorraine Arnold Rowan married John Sherman Cooper, who had served in the United States Senate as a Republican from Kentucky. They embarked on a life of politics and diplomacy that took them from the coal fields and hollows of Kentucky, where Mr. Cooper campaigned successfully to return to the Senate, to New Delhi and East Berlin, where he served as U.S. ambassador.

But they always returned to Washington, where their hospitality was such that John F. Kennedy and his wife Jacqueline dined at their house not long after Kennedy's inauguration as president of the United States. The Coopers gave an annual spring party for the Senate and Mrs. Cooper used to give teas for constituents from Kentucky. For one sizable dinner party in her garden she had tables set for two. At the end of each course the men moved to a different table.

The Cooper residence was on the Georgetown House Tour for many years.

Mrs. Cooper, who spoke French, Italian, Spanish and Russian, was equally effective as a hostess abroad, where entertainment was part of the business of diplomacy. In New Delhi, where the Coopers served from March 1955, to August 1956, she became friends of then prime minister Jawaharlal Nehru, who normally maintained his distance from Americans.

When the Coopers left New Delhi, the Times of India said, "Mrs. Cooper possesses unusual beauty and intellect, and a rare perception of political events."

In East Germany, where Sen. Cooper opened the U.S. Embassy in September 1974, Communist Party chief Erich Honecker accorded the couple the unusual courtesy of inviting them to lunch before their return to this country in December 1976.

Mrs. Cooper's personal style included dresses by Dior and parasols, which she sometimes carried even when swimming. She was 5 feet 6 inches tall and slender. She once said that she was able to keep her figure because "I decided as a schoolgirl in Florence to choose boys instead of cakes." She frequently was included on lists of best-dressed women.

In Kentucky, some of the senator's constituents thought his wife had "airs" and some commentators even suggested that she was that least desirable of all things in politics, a "liability." In fact, her interest in people and her natural ways made her an asset.

She also wrote a biweekly newsletter that was published in many Kentucky newspapers. It advised readers to take vitamin C every day and to increase the dosage at the first sign of a cold. It also included items such as this one about an international monetary conference:

"Deficit spending I understand well, as I have been doing it all of my life and know that it has worked for me -- but what, oh what, is 'balance of payments?'"

Mrs. Cooper was born in Pasadena, Calif. She was educated in California, Maryland and Italy. During World War II, she worked for Nelson A. Rockefeller on the Inter-American Affairs Council. She moved to Washington in 1948 and bought the house in Georgetown in 1953.

She was a president of the Senate Wives Club and a member of the Commission for the Restoration of Blair House, the Homemakers of Kentucky, the American Newspaper Women's Club, and the National Society of Arts and Letters. She was a director of the Asia Foundation and the Frontier Nursing Service of Eastern Kentucky. For many years she was a director of the R.A. Rowan Co., which was founded by her father in Los Angeles.

Her marriages to Robert McAdoo and Thomas Shevlin Jr. ended in divorce.

In addition to her husband, of Washington, survivors include three brothers, Robert A. Rowan, George D. Rowan and Louis Rowan, all of Pasadena.