| Dates | January 20–January 21, 1276 |
| Location | Arezzo |
| Dean | Vicedomino de Vicedominis |
| Camerlengo | Guglielmo di San Lorenzo (not a cardinal) |
| Protopriest | Simeone Paltineri |
| Protodeacon | Riccardo Annibaldi |
| Ballots | Pope elected in the 1st ballot |
| Elected Pope | Pierre de Tarentaise (took name Innocent V) |
Papal conclave, January 1276 (January 21 – January 22) – was the first papal election held under the rules of constitution Ubi periculum issued by Pope Gregory X in 1274, which established papal conclave. According to Ubi periculum Cardinals were to be secluded in a closed area; they were not even accorded separate rooms. No cardinal was allowed to be attended by more than one servant unless ill. Food was to be supplied through a window; after three days of the meeting, the cardinals were to receive only one dish a day; after five days, they were to receive just bread and water. During the conclave, no cardinal was to receive any ecclesiastical revenue.
Although several times before papal elections were held in the circumstances similar to those described by "Ubi periculum, for the first time such situation was formally required by the church law. For this reason, papal conclave of January 1276 can be considered the first papal conclave in history in the strictly legal sense of this word.
Pope Gregory X died on January 10, 1276 at Arezzo. At the time of his death there were probably fifteen cardinals in the Sacred College, but only thirteen of them participated in the subsequent conclave. Seven of them were created by Urban IV, four by Gregory X and one by Gregory IX:
Two cardinals were absent, including one created by Urban IV and one created by Innocent IV:
| Elector | Cardinalatial title | Elevated | Elevator | Other ecclesiastical titles | Notes |
|---|---|---|---|---|---|
| Simon Monpitie de Brie | Priest of S. Cecilia | December 17, 1261 | Urban IV | Papal Legate in the Kingdom of France | Future Pope Martin IV |
| Giovanni Gaetano Orsini | Deacon of S. Nicola in Carcere Tulliano | 1244, May 28 | Innocent IV | Inquisitor General; Protector of the Order of Franciscans | Future Pope Nicholas III |
On January 20, ten days after the death of Gregory X, fifteen cardinals assembled in the episcopal palace in Arezzo. In the first scrutiny on the following day they unanimously elected French Cardinal Pierre de Tarentaise, bishop of Ostia e Velletri, who took the name of Innocent V. He was the first Dominican Pope.
The Cardinals of the Holy Roman Church: Papal conclave of January 20-21, 1276
Vatican History: Konklave 1276 (Innozenz V)