Francisco Díaz Rojo, best known as simply Rojo, showed an early talent for drawing. However, he initially joined the Spanish Navy to pursue a military career. He left his job as a Navy telegraph operator after for years and settled in Barcelona, where he worked at the air traffic control center of Barcelona Airport.
He found his way to comic books in 1961, when he contributed his first artwork to the publications of Bruguera. He took the pen name Rojo to avoid confusion with Francisco Díaz Villagrosa. Rojo spent several years working for Bruguera before he joined Studio Ortega and worked on comic for the German market. For Bastei Verlag, he drew stories with 'Tom Berry', a character created by Carlos Giménez, and 'Buffalo Bill'. In the final stages of his career, he worked on animation series like 'Coby' and 'D'Artacán' through Claudio Biern Boyd's RGD studios.