Studied at the Academy of Fine Arts in Vienna with C. Griepenkerl, student and friend of Emil Jacob Schindler, whose wife he married after Sschindler's death (which made him stepfather of Alma Mahler-Werfel).
In 1897 co-founder of the Vienna Secession, which he left in 1905 together with the Klimt group. Supported the Klimt group until 1912 as art director of the gallery Miethke in Vienna, organised several exhibitions for foreign artists in Vienna and subsequently devoted himself to painting.
During this period he created chromolithographs and coloured woodcuts of large format.
In the 1920s he travelled to Italy and the South of France. In his later landscape paintings he overcame the two-dimensional style of the Secessionists to create works of an expressive, illuminated three-dimensional character.
Moll commited suicide in 1945.