Oskar Kokoschka, 93, a leading expressionist painter for more than 50 years, died Friday at a hospital in Montreux, Switzerland, after suffering a heart seizure at the nearby village of Villeneuve.

A perfectionist, Mr. Kokoschka estimated he had produced only about 500 pictures during the seven decades of his painting life, while "others do 500 in one month."

An emotional and intuitive painter, Mr. Kokoschka had departed from his early romantic influences by 1910 to begin a lifelong quest for what he called the "inner life."

"It is not my trade to unmask society but to seek in the portrait of an individual his inner life, that measure of all things, and never to rob humanity of its value," he wrote in a 1975 autobiography.

Eschewing the modern movement toward abstraction, he also spoke of his "vain search for Nature, as expressed in the 20th Century by the imitation of primitive art or the attempt to avoid the human image altogether."

His life's work includes hundreds of penetrating portraits of the great and near-great; self-portraits that provide visual attempts at self-interpretation; landscapes and cityscapes painted from a bird's eye view in the classic tradition of Venetian masters Canaletto and Guardi, and allegorical subjects favored by the old masters such as Biblical and Shakespearean figures, still lifes and the glory of ancient Greece.

All were characterized by his use of hectic brush strokes, violent colors, freshness and boldness and a feeling of freedom. His portraits, sometimes experimental, were always forceful characterizations, almost to the point of caricature.

Born in the Austrian village of Pochlarn, Mr. Kokoschka spent his formative years in the baroque cities of Salzburg and Vienna. As a student at the Vienna School of Decorative Art he came under the influence of Viennese painter Gustave Klimt. His first public exhibition in Vienna in 1908 so shocked the public that he soon moved to Berlin, where he spent several years as an illustrator for the famous art magazine "Der Sturm."

The breakup of a tempestuous three-year love affair with Alma Mahler, widow of the composer Gustave Mahler, led to his enlisting in the Austrian cavalry in World War i, during which time he was badly wounded.

A staunch anti-Nazi, he was among the first to be branded as "degenerate" by Hitler and he was forced to find refuge in London in the late 1930s. He lived there for several years, became a citizen and married Olga Palkovsky in 1941.

During his London years he painted a number of "political pictures, not because I felt a political involvement of any kind" but "to see war this time from the other side of the barricades," he said later.

Mr. Kokoschka's paintings in recent years include portraits of Pope Pius XII, Agatha Christie, Pablo Casals and Golda Meir. His work is displayed in the world's leading museums, including the Museum of Modern Art in New York City and the Tate Gallery in London.

"I would like to live at least 200 years," he said in 1974. "I would like to be the last one sitting on a tree so I can watch. I know that I would be doomed as well. But I would like to know how the end will come to mankind. I am an explorer.""

Mr. Kokoschka continued to paint for several hours a day until shortly before his death.

Survivors include his wife.