A conclave was held from 14 December 1830 to 2 February 1831 to elect a new pope to succeed Pius VIII, who had died on 30 November. Of the 45 members of the College of Cardinals, all but nine attended. On the 83rd ballot, the conclave elected Cardinal Bartolomeo Cappellari, the prefect of the Congregation for the Propagation of the Faith. After accepting his election, he took the name Gregory XVI.
Background
Pope Pius VIII died on Thursday, 30 November 1830, at the age of sixty-nine. On 11 December, Monsignor Benedetto Cappelletti, the governor of Rome, informed the cardinals that there was a conspiracy in Rome involving the Bonaparte nephews of Cardinal Joseph Fesch. One in custody had been released to the Russian minister, since his mother was the Russian-born Catharina of Württemberg. Fesch refused to ask his nephews to leave Rome. A paper bomb exploded under the windows of the conclave. Bartolomeo Pacca presided as dean of the College of Cardinals.
Initially the chief candidates included Emmanuele De Gregorio and Bartolomeo Pacca, who had been papabili in the 1829 conclave, plus Giacomo Giustiniani, who was a long-serving papal diplomat but who was vetoed by King Ferdinand VII. Giustiniani had served as nuncio at Madrid and provoked the hostility of the prime minister in ecclesiastical matters, and Queen Christina regarding the succession. Cardinal Tommaso Bernetti, who vied with Albani for the position of secretary of state, threw his support to De Gregorio.
Cappellari appeared as an alternative to both De Gregorio and Macchi only when the conclave was well-advanced, but even though Albani worked against him, Cappellari eventually took the lead and won the election, taking the papal name Gregory XVI.
No conclave since has lasted as long as a week, but at the time no conclave since 1667 had lasted fewer than three weeks. The conclave took eighty-three ballots to deliver a two-thirds majority to a candidate, whereas no conclave since has taken more than fourteen.
Cappellari, then a Camaldolese priest and prefect of the Congregation for the Propagation of the Faith, was also the last pope not a bishop when elected.
{|class="wikitable sortable" style="width:230px; float:center; margin:auto;"
|+Cardinal electors by region
|-
!scope="col"|Region
!scope="col"|Number
|-
|style="text-align:center" scope="row"|Italy
|style="text-align:center"|36
|-
|style="text-align:center" scope="row" data-sort-value="Europe, Rest of"|Rest of Europe
|style="text-align:center"|9
|-
|style="text-align:center" scope="row" data-sort-value="America, North"|North America
|style="text-align:center"|0
|-
|style="text-align:center" scope="row" data-sort-value="America, South"|South America
|style="text-align:center"|0
|-
|style="text-align:center" scope="row"|Asia
|style="text-align:center"|0
|-
|style="text-align:center" scope="row"|Oceania
|style="text-align:center"|0
|-
|style="text-align:center" scope="row"|Africa
|style="text-align:center"|0
|-
!scope="row"|Total
!45
|}