The London Missionary Society (L.M.S) now the Council for World Mission, commenced its work in South Travancore in1806. Vedamanickam Maharasan Desikar was the first Christian who invited William Tobias Ringeltauble the first Missionary to come in Travancore. He crossed into Aruvamozhi on April 25th 1806.
The South India United Church (S.I.U.C) was formed on 25th July 1907 with nine member church denominations of which the South Travancore L.M.S Church was one. The South Travancore Church Council was constituted in 1921 with the Tamil and Malayalam churches put together. The Church of South India(C.S.I) was inaugurated on 27-09-1947 and the member churches adopted episcopacy as part of the church order. The Rt. Rev. A. H. Legg, was consecrated on 27-09-1947 and installed as the first Bishop of the South Travancore Diocese on 13-10-1947.
The South Travancore Diocese was bifurcated into the Kanyakumari Diocese and the South Kerala Diocese in 1959 and the Rt. Rev. A. H. Legg continued to be the first Bishop of the South Kerala Diocese till be returned to England in 1965. The Rt. Rev. William Paul Vachalan was consecrated and installed in the South Kerala Diocese on 2-7-1967. He passed away o 5-11-1972 while in service. The Rt. Rev. Isaiah Jesudason, was consecrated and installed in the South Kerala Diocese in 5th August 9973. He was Deputy Moderator of the Church of South India from 1980-81 and Moderator from 1982-1987. He served as a Central Committee member of the W..C.C Hon.Doctorate of Divinity was conferred upon him in 1988. He retired from active service on 14th February 1990 on completion of 65 years of age.
The Rt. Rev. Dr. Samuel Amirtham was consecrated and installed as Bishop of the Diocese on 20-05-1990. He was director of the Programme on Theological Education and Director of the Ecumenical Institute, Bossey of the WCC 1980-1990. Serampore University conferred on him a honorary doctorate in 1987. He retired from active service on 19the August 1997. Rt. Rev. Dr. J. W. Gladstone, was consecrated and installed as Bishop on 16-9-1997. He was the principal of KUT seminary, Trivandrum. Most Rev. Dr. J. W. Gladstone was selected as Moderator of CSI during 2008.