Born and educated in Bologna, he completed his theological studies before he had reached the minimum age for ordination as a priest; he was ordained in 1.797.
In the same year, he became professor of Arabic at the University of Bologna.
He later lost the position for refusing to take the oath of allegiance required by the Cisalpine Republic, which governed Bologna at the time.
In 1.803 he was appointed assistant librarian of the Institute of Bologna, and soon afterwards was reinstated as professor of Oriental languages and of Greek.
The chair of Oriental languages was suppressed by the viceroy in 1.808, but again rehabilitated on the restoration of Pope Pius VII in 1.814.
Mezzofanti held this post until he left Bologna to go to Rome in 1.831 as a member of the Congregation for the Propagation of the Faith (Congregatio de Propaganda Fide), the Catholic Church's governing body for missionary activities.
In 1.833, he succeeded Angelo Mai as Custodian in Chief of the Vatican Library, and in 1.838 was made cardinal of the title of St. Onofrio al Gianicolo and director of studies in the Congregation for the Propagation of the Faith.
His other diverse interests included ethnology, archaeology, numismatics, and astronomy.
List of languages spoken
Mezzofanti was well known for being a hyperpolyglot who fluently spoke thirty-nine languages.
Also, the study by Russell indicates that many of the dialects are so different that they actually should be seen as a separate language.
Classifying the languages and dialects according to today's language system, over 150 years later, would be a separate study.
The list, in the conclusion of his study :
"Languages frequently tested, and spoken with rare excellence."
Czechish, or Bohemian