Pablo Picasso | Pablo Neruda | Pablo Casals | Juan Pablo Montoya | Pablo Fanque | Pablo Milanés | Pablo Alborán | Pablo Escobar | Pablo Puyol | Pablo Palazuelo | Juan Pablo Pérez Alfonso | San Pablo | Petey Pablo | Pablo Márquez | Pablo Cruise | Pablo Armando Fernández | Pablo | Augustus Pablo | Pablo Trapero | Pablo Sandoval | Pablo de Olavide University | Pablo Curatella Manes | Pablo Batalla | Luis de Pablo | Juan Pablo Bonet | Steve "Pablo" Davis | San Pablo Creek | Pablo Zalba Bidegain | Pablo Solón Romero | Pablo S. Gomez |
Over the years he performed works by composers such as Johann Sebastian Bach, Ludwig van Beethoven, Béla Bartók, Ernest Bloch, Johannes Brahms, Claude Debussy, George Frideric Handel, Joseph Haydn, Paul Hindemith, Darius Milhaud, Sergei Prokofiev, Robert Schumann, Grigoraș Dinicu, George Enescu, César Franck, Fritz Kreisler, Ottokar Nováček, Gaetano Pugnani, Pablo de Sarasate and Pyotr Ilyich Tchaikovsky.
He became a piano accompanist and teacher, working with Huberman, Pablo de Sarasate, Egon Wellesz, and the Rosé Quartet.
In 1903, with financial support from the patron François Franck, Mortelmans founded the Maatschappij der Nieuwe Concerten ("Society of New Concerts") in Antwerp, which attracted notable guest conductors and artists such as Gustav Mahler, Siegfried Wagner, Hans Richter, Richard Strauss, Sergei Rachmaninoff, Pablo de Sarasate, Jacques Thibaud, Pablo Casals, and Fritz Kreisler.