Hartmann was a student of Holger Byrding, studied at the conservatory and at the Royal Opera School in Copenhagen from 1957 to 1962.
He made his debut at the opera house in Copenhagen in 1962 as Rodolfo. He stayed there until 1967. He continued to sing in Copenhagen
as a guest.
From 1966 to 1972, he sang in Hamburg. His further guest appearances were in:
Bayreuth (1965 and 1966 as Walther von der
Théâtre de la Monnaie Bruxelles: Fidelio as Jacquino on 30 October/2/4/6 November
1965, with Ernst Kozub (30 October, 2/6 November)/Niels Möller (4 November), Anja Silja,
Theo Adam (30 October)/Eduard Wollitz (2/4/6 November), Gustav Neidlinger, Gerd Nienstedt, Rita Bartos (30
October/2 November)/Ghislaine Morèze (4/6 November), John Geentjens, Manfred Dorner, André Vandernoot;
Staatsoper Wien: Arabella
on 24 February 1970 as Matteo with Kurt Böhme, Christel Goltz, Lisa Della Casa, Olivera Miljakovic, Eberhard Waechter, Fritz Uhl, Hans Christian,
Herbert Lackner, Mimi Coertse, Elisabeth Höngen, Berislav Klobučar;
In Hamburg, he took part in the world premieres of Hamlet by R. Searle (1968 as Laertes) and Belagerungszustand by M. Kelemen
His repertory included Pylades, Tamino, Florestan, Froh, Steuermann, Narraboth, Matteo, Jim Mahonney,
Ismaele, Cassio, Vogelsang, des Grieux (Manon Lescaut), Pinkerton, Luigi, Cavaradossi, Števa, Lenskij,
Grigorij, Jonathan (Saul og David), Leander (Maskarade), Alfred, ...
In 1970, he got so sick that it hampered his career, which he gave up in 1972.
He recorded for Vox, Polydor, Unicorn (complete recording of Saul og David in 1978), and Danacord
(live and studio recordings 1963–66 – DACOCD623-24).
His performance as Cavaradossi with Lone Koppel and Ib Hansen was recorded in 1964 for TV.
Reference: Kutsch & Riemens