Mattei was ordained a priest in 1768 and appointed in 1777 to the Archbishop of Ferrara. He received his episcopal consecration Cardinal Bernardino Giraud. In 1779 Pius VI created. him. pectore in Cardinal, which was published in 1782 and showed him a cardinal priest, the titular church of St. Balbina to 1786, he was created cardinal priest of Santa Maria in Aracoeli, finally appointed in 1800 to Cardinal Bishop of Palestrina and 1809 for Cardinal Bishop of Porto e Santa Rufina. It was when the church fell into distress by the French Revolution, together with Cardinal Francesco Maria Pignatelli as legate in Italy go. Since he refused Napoleon's marriage with the Archduchess Marie -Louise of Austria recognition, forbade him the emperor wearing his red Amtsrobe and Mattei was a so-called black cardinal. In 1814 he was elected to the Cardinal Dean and Pius VII gave him the bishopric of Ostia suburbicarian.
Mattei took part in the conclave of 1799/1800, which elected Pope Pius VII. He was even touted as the candidate of the pro- Austrian faction, but did not get enough votes. In April 1820, he died after a brief illness.
- Roman Catholic Bishop (18th Century)
- Roman Catholic Bishop (19th Century )
- Cardinal (18th century)
- Cardinal (19th Century )
- Cardinal Dean
- Historical person (Italy )
- Born in 1744
- Died in 1820