In 1919, Hupp received his doctorate in Bonn with the dissertation Entwicklungsgeschichte der Kunst Carl Friedrich Lessing.
In 1922 he published it under the title Karl Friedrich Lessing, a transitional master of the Düsseldorf school of painting from Romanticism to Realism.
[1] On 1 March 1934, Hupp succeeded Karl Koetschau [de] as full-time director of the Kunstmuseum Düsseldorf,[2] he had already held it provisionally since 1933.
As Düsseldorf museum director, he opened the exhibition "Galerie der Neuzeit" on 17 July 1935, a compilation of 20th-century paintings and sculptures whose concept he had been working on since 1934.
[5] In the summer of 1935, the mayor of Düsseldorf Hans Wagenführ [de] decided to focus the collection entirely on regional art.