He and his brother Alfredo began their training with María Suárez Fiol, (born in Madrid, 1897 – died in Las Palmas de Gran Canaria, 1987).
He started singing in the Choir of the School of the Heart of Maria, and made an audition for Soloists in the Philharmonic Society of Las Palmas.
Mrs Llopart's legacy of exquisite technique and knowledge of voice production was passed on to her students, Alfredo Kraus, Renata Scotto, Anna Moffo, Fiorenza Cossotto, Ivo Vinco, Greek soprano Elena Suliotis, Venezuelan coloratura soprano Cecilia Nuñez Albanese, and Francisco Kraus.
In December 1960, Francisco made his Debut in the “Teatro Comunale Giuseppe Verdi” in Trieste with the Moussorgsky opera Khovanshchina in the role of Shaklovity and using the stage name Franco di Marco.
In 1966 a contract with the company of Maria Francisca Caballer and Agustín Lisbona, to perform in the National Theater of Caracas, “Teatro Nacionál,” took him to Venezuela for one long season.
His break from the Operatic scene was not total, however, and in the 1970s he took part in several seasons of Zarzuela with the Isaac Albéniz Company of Juan Jose Seoane, performing all over Spain and the Spanish Islands.
He was very active as a teacher and some of his students were: Fanny Arjona soprano, Amelia Salazar, Natacha Valladares, Marisol Gil, Alfredo Olarte, Rosaura Longa, and Biella Da Costa.
In 1987, he returned to Spain to teach voice technique at the Conservatory of the “Gran Teatre del Liceu” in Barcelona, where he taught until his retirement.
Retirement His last public performance took place in Las Palmas de Gran Canaria in 1996, where he was awarded the Gold medal of the City.
In November 2000, Francisco Kraus received the tribute of the Canary Island “Friends of the Zarzuela”, who gave him a Plaque in recognition of his long career.