Mgr.Hebert was elected as Co-adjutor already in 1806 with the title of Bishop of Halicarnasse. Due to his illness and at his own reluctance to became bishop, his ordination was delayed. When Mgr.Champenois died in 1810, he was ordained Bishop on 2nd March 1811 from the hands of a Carmelite Bishop of Syrian Rite at Verapoly. For this, Mgr.Hebert, a sickly man had to cover 1000kms traveling on Bullock cart for his consecration.
During the period of Mgr.Hebert, cholera and famine had their toll of woes. In 1829 there was a severe attack of cholera. And due to failure of monsoons, a general famine followed. Mgr.Hebert went to the extent of having the sacred vessels melted and sold out to give relief to the poor.
In 1827, Viscount Desbassyns invited to Pondicherry the Sisters of St.Joseph of Cluny. On 13th September 1836 Mgr.Bonnand, who was on his pastoral tour, received a letter from Mgr.Hebert, asking him to return to Pondicherry immediately. On his arrival he found Mgr.Hebert unconscious and dying. Mgr.Hebert died on the 3rd of October 1836, without ever using the title of Apostolic Vicar conferred on him. It was due to the insistence of Mgr.Hebert that Rome decided to create several Apostolic Vicariates. In 1832 the Vicariate of Madras was created; in 1834 the vicariates of Calcutta, Sindhana and Ceylon; on the 8th of July 1835, the vicariate of the Coromandal coast with Mgr.Hebert holding the title was created. At the request of Mgr.Hebert the Madurai Mission was detached from the Malabar Mission on the 23rd of December 1836.
