[1] He made his operatic debut as a tenor at the municipal theatre of Eger in 1941, in the title role Canio in the German-language staging of Leoncavallo's Pagliacci (Der Bajazzo).

[2] Cordes was known for leading baritone parts in Italian opera, such as Enrico in Donizetti's Lucia di Lammermoor, the title role in Verdi's Nabucco, Egbert in his Aroldo, and Ford in Falstaff.

In German language versions of Verdi, he played Luna in his Il trovatore (Der Troubadour), and Don Carlos in La forza del destino (Die Macht des Schicksals).

[1] The Hamburger Archiv für Gesangskunst issued an overview of his art in a collection CD-Edition Marcel Cordes of twelve CDs in four boxes: Giuseppe Verdi, Belcanto & Verismo, Opern Streifzug of German and European Opera, and Moderne – Konzert – Lieder (Contemporary – concert, song recital).

[5] A short overview of single scenes was published on CD, titled Dokumente einer Sängerkarriere (Documents of a singer's career) by Preiser Records.