The Vicariate Apostolic of Cambodia was erected on 30 August 1850. Since 1860 it was responsible for the provinces Phsar Dek, Châu Đốc and Sóc Trăng of lower Cambodia, now part of Vietnam. In 1924, it was renamed as Vicariate Apostolic of Phnom Penh. On 20 September 1955, the vicariate became responsible for all of Cambodia. In 1968, the vicariate was split into three parts, with the Apostolic Prefecture of Battambang responsible for the north west and the Apostolic Prefecture of Kompong Cham for the north east of the country. During the rule of the Khmer Rouge, all religious activities were forbidden, and many Catholics were persecuted, especially priests and other ordinaries. Also many Vietnamese Catholics, the majority of Catholics in Cambodia, were either executed or expelled from the country. Most churches were also destroyed. The number of Catholics in the area of the vicariate fell from about 30,000 to less than 10,000. In 1989, the new constitution of Cambodia allowed freedom of religion once again, although the preaching of Christianity was still forbidden by the Council of Ministers. In March 1990, the Cambodian government gave its approval for a group of Catholics to celebrate Easter Sunday, the first public worship in Cambodia in 15 years. On 24 December 2009 the French priest Olivier Schmitthaeusler, M.E.P. was named Coadjutor Vicar Apostolic of Phnom-Penh and Titular Bishop of Catabum Castra. He succeeded to bishop Destombes on 1 October 2010. On 1 May 2015 the Cambodian Catholic Church opened an official diocesan inquiry for the martyrs in Tangkok, Kampong Thom Province, where Bishop Joseph Chhmar Salas died during the Khmer Rouge regime in 1977. The inquiry looks after the presumed martyrdom of at least 34 persons executed or let to die from April 1975 to 1978.
Bishops
Ordinaries
Jean-Claude Miche, M.E.P.: 1850 – 1869
Marie-Laurent-François-Xavier Cordier, M.E.P.: 18 June 1882 – 14 August 1895
Jean-Baptiste Grosgeorge, M.E.P. 28 January 1896 – 1 March 1902
Jean-Claude Bouchut, M.E.P.: 23 July 1902 – 17 December 1928
Valentin Herrgott, M.E.P. 17 December 1928 – 23 March 1936
Jean-Baptiste-Maximilien Chabalier, M.E.P.: 2 December 1937 – 11 June 1955
Gustave-André-Ferdinand Raballand, M.E.P.: 29 February 1956 – April 1962
Yves-Georges-René Ramousse, M.E.P.: 12 November 1962 – 1976
Joseph Chhmar Salas: 30 April 1976 – September 1977
Yves Ramousse, M.E.P.: 25 July 1992 – 14 April 2001
Emile Destombes, M.E.P.: 14 April 2001 – 1 October 2010
