Born in Basel, Moeschinger, son of a merchant, completed his musical studies in Bern, Leipzig (composition with Paul Graener, piano with Robert Teichmüller) and Munich (composition with Walter Courvoisier).
After several seasons as an ensemble pianist in café houses, Moeschinger settled in Bern, where he taught privately as a piano and theory teacher, and from 1937 also at the University of the Arts Bern, and resumed his compositional activities.
In 1943, health problems led him to settle in the Valais mountain village of Saas Fee.
Reading Thomas Mann's musical novel Dr. Faustus and the subsequent correspondence with the writer in 1948 encouraged him to integrate the twelve-tone technique into his work.
[2] Traces of Moeschinger's church music can be found in the hymnal of the Protestant Reformed Churches of Switzerland: Gesangbuch der Evangelisch-reformierten Kirchen der deutschsprachigen Schweiz [de] 215 Herr wir warten arm und hungrig (same melody also 318, 553 and 717) and 256 Es ist ein Wort ergangen.