Switching to music, he enrolled in 1909 in the Hoch Conservatory in Frankfurt,[1] where he studied harmony with Bernhard Sekles and composition with Iwan Knorr.

[citation needed] Hoboken's wealth enabled him to collect early editions and manuscripts of music from Bach to Brahms.

[1] In 1922 Hoboken married Annemarie Seidel (1895–1959), an actress whom he had rescued from ill health resulting from living in the dank basement apartment of her former lover.

The evening passed extremely well; the complete naturalness in the social gathering, and in our relationship to the musicians; the rooms; the beautiful, sumptuous meal and its presentation (for which we offered the chef a toast, with applause): these made an exceptional impression on us all.

The financial strains of alimony and a new household lessened what Hoboken could spend on projects involving Schenker, including the photographic archive, and their relationship "soured".

[14] The Haydn catalog that now bears Hoboken's name (see below) was begun in card format in 1934; work continued until the publication of the third and final book volume in 1978.

[1] His greatest accomplishment, the work of over forty years,[15] was the "Hoboken catalog", or more formally Joseph Haydn, Thematisch-bibliographisches Werkverzeichnis.

The catalog proved influential and Haydn's works today are often referred to by the "Hoboken number" (usually abbreviated to "Hob" or just "H") by which they are designated in this catalogue.

Nevertheless, Hoboken's protracted study established the corpus of Haydn's huge output, dealt with the problem of arrangements and supposititious works and generally brought order and identity to a vast area where much confusion, contention and uncertainty reigned for 150 years.

[2] Hoboken's services to scholarship were recognized early on in 1932, when he received the Grosse Silberne Ehrenzeichen[16] from the government of Austria; later on would follow multiple honorary degrees, a knighthood, and so on.