cofounder of the Order of the Most Holy Trinity for the Redemption of Captives, commonly called Trinitarians (Trinitarian), or Mathurins, a Roman Catholic mendicant order originally dedicated to freeing Christian slaves from captivity under the Muslims.

John received his early education at Aix-en-Provence, Fr., and then retired to a hermitage near Faucon; he later studied theology at Paris, where he was ordained priest. In 1197 he planned to form a group of monks to rescue Christians captured by the Muslims and enslaved in Africa. He may have been joined in this venture by the hermit Felix of Valois; recent historians, however, have come to doubt whether Felix actually existed. At Rome in 1198, John obtained approval for his order from Pope Innocent III, who made John the first superior general. On his return to France, John, possibly accompanied by Felix, was received by King Philip II Augustus, who sanctioned the establishment of the Trinitarians in France. John founded the motherhouse at Cerfroid in the region of Picardy and adopted a severe form of the Rule of St. Augustine of Hippo. In 1655 John's relics were transferred to Madrid; his cult was officially approved in 1655 and again in 1694.

The biographical details given above are those generally accepted as authentic. According to the spurious hagiographies of 15th- and 16th-century Trinitarians, John and Felix founded other French convents and dispatched some of their members to the Crusades. In 1202 John supposedly went to Tunis, Tunisia, and liberated 110 prisoners there, after which he ransomed several more Christian slaves in Spain. His second voyage to Tunis was recorded to have been a near calamity: severely persecuted by the Muslims, he embarked and managed to reach Ostia Antica, Italy, even though his ship was badly damaged. These accounts, however, and the miracles attributed to John were discovered in the 20th century to be fabrications; the hagiographical problem is explained in P. Deslandres' L'Ordre des Trinitaires pour le rachat des captifs, 2 vol. (1903).