| Papal conclave February–August 1740 | |
|---|---|
| Dates and location | |
| 18 February – 17 August 1740 Apostolic Palace, Papal States | |
| Key officials | |
| Dean | Pietro Ottoboni, Tommaso Ruffo |
| Sub-dean | Tommaso Ruffo, Lodovico Picco della Mirandola |
| Camerlengo | Annibale Albani |
| Protopriest | Armand-Gaston de Rohan-Soubise |
| Protodeacon | Lorenzo Altieri |
| Elected pope | |
| Prospero Lorenzo Lambertini Name taken: Benedict XIV | |
 | |
The 1740 papal conclave (18 February – 17 August), convoked after the death of Pope Clement XII on 6 February 1740, was one of the longest conclaves since the 13th century.
The initial favourite to succeed as pope, the elderly Pietro Ottoboni (1667–1740), Dean of the College of Cardinals, died shortly after the beginning of the conclave, and cardinals loyal to the House of Bourbon repeatedly proposed Pompeo Aldrovandi, but eventually had to accept that he could not secure two-thirds of the votes.
After six months, other possible candidates had also failed, and Cardinal Prospero Lambertini, Archbishop of Bologna, who had been a cardinal since 9 December 1726, was elected. He took the name Benedict XIV.