After a short stint of chemical studies, Frankl turned to painting. He was taught by Anton Kolig in Carinthia for some months in 1920/21. After that, he taught himself. He studied the Old Masters at the Kunsthistorisches Museum and examined Romanic and Gothic sculpture. He took study trips to North Africa, Germany, France, Italy and the Netherlands, interrupted by frequent stays in the Austrian and Swiss Alps. He also worked as a sculptor from 1929 to 1935. Frankl emigrated to England in 1938. He returned to Vienna for the years 1947/48 and gave lectures in art history at Vienna University. Frankl’s favourite subjects were landscapes, cityscapes, still lifes and portraits. Colour is of special importance in his works, which adhere to strict structural principals, influenced by Cézanne. Apart from his oil paintings, Frankl also made many watercolours and etchings. In the mid-1960s, he created studies of medieval sculptures as well as the cycle "In Memoriam".