Kosa was a draftsman and a painter of landscape, portraits, and murals. He studied at the Academy of Fine Arts in Prague, at the Ecole des Beaux Arts in Paris, and at the California Art Institute, ***. He became a naturalized citizen in 1927 and the following year married Mary Odisho. He maintained a studio in Los Angeles, and worked for Twentieth Century Fox as a scenic painter.
He painted California scenery, especially that of the Sierra Mountains, as well as scenes from the old quarter of Los Angeles, and of Mexico. In 1941 he exhibited twenty-four paintings of the California landscape at the Biltmore Salon, ***, and that same year had an exhibition of his watercolors and oils at Macbeth Galleries, New York. In 1957 he exhibited fifty non-objective canvasses, in a style with which he had experimented for the previous three years, at the Cowie Galleries in the Biltmore Hotel, Los Angeles.
Kosa's prizes include the National Academy's Cannon Prize which he won in 1951 for First Snow at Gorman, and the Childe Hassam Purchase Prize which he won at the Academy's annual exhibition in 1952. He won prizes from the American Watercolor Society, the California Art Club, the Oakland Art Gallery, and the California Watercolor Society.
Kosa made the following statement on a biographical questionnare which he completed for the National Academy:
The experience of art is my form of salvation. It is through it that I am brought to a more intimate understanding and feeling of life and human relationships. Whatever I do is the result of a philosophy based upon this fact.
