Career
He was one of the oldest Roman Catholic bishops and Dutch bishops. Demarteau was appointed Vicar Apostolic of the Diocese of Banjarmasin on 6 January 1954 along with Titular Bishop of Arsinoë in Cypro and was consecrated bishop on 5 May 1954. He was appointed bishop of the Diocese of Banjarmasin and served until his resignation on 6 June 1983.
Demarteau died on 5 December 2012 in Suaka Insan Hospital (Rumah Sakit Suaka Insan:Indonesian).