Ordained in 1818, he was successively a member of the Missions de France, rector of Sainte-Geneviève (rue d'Enfer) and chaplain of the Infirmerie Marie-Thérèse (92 avenue Denfert-Rochereau).
His love of missionary life made him decline episcopal honours and a chair at the Sorbonne, but was no obstacle to his literary pursuits.
Besides many contributions to the Bibliographie Catholique, Caillau wrote Instructions sur l'oraison mentale (Paris, 1833), a French translation of Tertullian's De Spectaculis (Paris, 1835), several monographs on Our Lady's Sanctuaries: Roc-Amadour (1834), Loretto (1843), N.D. de Puy (1846), Litanies du St. Nom de Jesus (Paris, 1845), Les nouveaux illuminés (Michel Vintras) (Orléans, 1849), etc.
He is best known, however, by the following works: A similar project of a Bibliotheca Mariana resulted only in the publication of a few opuscula of Ephrem the Syrian, Bonaventure, Idiota (Jordan), and the Marial monographs noticed above.
III and IV of D. Ceillier's Histoire des auteurs sacrés (1838-9); and Lettres de Scheffmacher (1839).