Born in Budapest, he became a distinctive modernist painter whose career spanned several decades.
Kádár began his studies in 1896, he travel to Paris and Munich. He attended the Academy of Fine Arts in Budapest and won the Kohner prize in 1910.
Kádár's early works, which he began exhibiting in 1918, showed the influence of the Secessionists and Post-impressionists. In 1923 he exhibited with his friend Hugo Scheiber in Berlin at Walden's Der Sturm Gallery; 57 of his works were shown. Der Sturm was one of the most important avant-garde galleries in Europe, Kádár continued to exhibit there for several years.
Kádár traveled to the United States and stayed for a year. He exhibited with the Société Anonyme at the Brooklyn Museum. In 1929 he returned to Budapest to exhibit his works in his home country.
Kádár was personal friends with Chagall, Picasso, Kandinsky and Kokoschka. Like his contemporaries his style evolved through the decades of the 20th century. Always a modernist, his works have elements of Cubism, Futurism, Neo-Primitivism, Constructivism, and Expressionism. His subjects range from Hungarian legends,
metaphysical, portraits, and fanciful decorative themes.