Career
He also wrote songs for other artists, including "Tractor amarillo" which was a hit for the group Zapato Veloz in 1993. And "Louisiana Puerta del Colegio" (1991) and "Mi Amada" (1993), hits for the Mexican group Magneto (along with Alberto Estébanez). He released several solo singles in the 1990s, and "Hasta el final del mundo", a duet with Mónica Naranjo.
In 1998, Herzog was chosen by broadcaster TVE as the Spanish representative for the 43rd Eurovision Song Contest with the song "" ("What Will I Do Without You?").
At the contest, held in Birmingham on 9 May, "" finished in 16th place of 25 entries. In 2001, Herzog joined the team of reality television singing competition Operación Triunfo, which served to select the Spanish entrant for the 2002 Eurovision Song Contest.
In 2007 he was again involved in Spain"s Eurovision selection as one of five judges on the show Misión Eurovisión 2007.