Thomas Pfeiffer already unfolded his concert activities while still a student. He made guest appearance at the the Art Festival of Weimar with a "Goethe evening song" and with Schubert song cycle Die Schöne Müllerin at the Marienbad Festival in Tschechien, Mahler's of Lieder eines Fahrenden Gesellen, he made music with the Vogtland Philharmonic in Reichenbach and Greiz. He was soloist in J.S. Bach's Mass in B minor (BWV 232) with the orchestra "Les Amoureux" in Paris and with the Festival of the Besancon in France, with opera productions of works by Mozart, Haydn, Felix Mendelssohn and Smetana; with the Rossini Festival in Bad Wildbad; the Festival of Ludwigsburg, at the Danube Festival Week in Austria and with "Ars-Musica" in Berne. Beside numerous Lieder recitals and oratorio concerts in his homeland, the tours abroad with renowned choirs represent further important stations of his singing career. So, among other things, Thomas Pfeiffer has appeared with the Kantatenchor Tübingen in Orff's Carmina Burana in Spain and Bach's Matthäus-Passion (BWV 244) in Greece; with the Kammerchor Stuttgart in works of Jan Dismas Zelenka and Bach in Italy and Austria, with the Bachchor Karlsruhe in Händel's Salomo in France. Among his most important CD productions: The three Schubert song cycles, Lieder by Richard Strauss, Rückert-Vertollungen (Schubert, Clara Schumann and Robert Schumann, Johannes Brahms, Mahler, Reutter, Komma), Beethoven Lieder, the Mozart's Singspiel Zaide and and Rosssini's, Petite Messe solennelle. He has also participated in numerous TV and radio productions. Thomas Pfeiffer particpates in the jury of music competitions and gives singing courses, among other things for the German Tonkünstlerverband and the Intemationalen working group for music. Since 1992 he is a professor for singing at the National University for Music and Art in Stuttgart.