He first worked as a composer and pianist, but became interested in folk music and performed field research, collecting hundreds of sound documents of songs, pieces and dances.

He compiled his scientific main opus, a collection of Austrian folk music in 23 volumes entitled Corpus Musicae Popularis Austriacae (COMPA), after he was emerited.

[2] Supported by Josef de Sordi, a player from the Wiener Symphoniker whom he had met in the US,[2] he moved to Vienna to study at the Musikakademie, composition with Alfred Uhl, conducting with Hans Swarowsky,[1][3] and piano with Franz Eibner.

[1][2][3] Simultaneously he had contact to the Volksliedarchiv for Vienna and Lower Austria, where he studied and analysed the material, conducted field research, like earlier Béla Bartók and Zoltán Kodály.

[1] His scientific main opus is a collection of Austrian folk music in 23 volumes entitled Corpus Musicae Popularis Austriacae (COMPA),[3][4] compiled after he was emerited.

He planned and presented a monthly radio series on ORF in Lower Austria, entitled "AufhOHRchen", offering 117 episodes of Volksmusikalische Kostbarkeiten (Treasures of folk music).

[5] He had begun in 2022 to pass his Vorlass [de], a substantial collection of research reports, manuscripts, books and sheet music, to Österreichisches Volksliedwerk.

[1] In Deutsch's honour, the Austrian Ministry of Culture [de] created the "Walter-Deutsch-Preis" in 1994, awarded in recognition of special achievements in the field of folk music research.