He belonged to the noble Florentine
Acciaioli family, third of the ten children of Senator Ottaviano Acciaioli and Maria Acciaioli and was the uncle of Cardinal
Filippo Acciaioli (1700 – 1766). He graduated in law in Rome. In 1657 he became Auditor camerae at the
Apostolic Camera. In the consistory of 29 November 1669 he was appointed Cardinal by
Pope Clement IX despite not having yet received his
minor orders. Only in March of the following year, he received the title of Cardinal-deacon assigned to the deaconry of
Santi Cosma e Damiano. He was
Papal legate to the city of
Ferrara on several occasions for several years. In 1689 he became
Cardinal protodeacon and in October of the same year he opted for the deaconry of
Santa Maria in Via Lata, but already one month later he became Cardinal priest of
San Callisto. In 1690 he was appointed Abbot commendatory of the abbey of Sant'Angelo de Frigillo in
Mesoraca, Calabria. Three years later he became
Cardinal bishop of Frascati, receiving episcopal consecration on 8 November 1693. In 1700 he opted for the
Suburbicarian Diocese of Porto–Santa Rufina. He became
Dean of the Sacred College in 1715 and had the title of Cardinal bishop of the
Suburbicarian sees of Ostia and
Velletri, also assuming the office of Governor of Velletri. In 1717 he became secretary of the
Congregation of the Sacred Roman and Universal Inquisition, a position he held until his death. His body is buried in the church of San Lorenzo, near the
Florence Charterhouse, built by a member of his family in the 14th century.
Conclaves Niccolò Acciaiuoli participated in the following conclaves : •
1669–1670 papal conclave, which elected Pope Clement X •
1676 papal conclave, which elected Pope Innocent XI •
1691 papal conclave, which elected Pope Innocent XII •
1700 papal conclave, which elected Pope Clement XI ==Sources==