Situated in the centre of Kerala, the eparchy of Kothamangalam with 4,800 square kilometers covers the taluks of Kothamangalam, Devikulam, Kunnathunad, Udumbanchola and Thodupuzha.
Malayalam, English and Tamil are the spoken languages in the diocese.
The diocese of Kothamangalam was established in 1956, and was inaugurated in January 1957. Mar Mathew Pothanamuzhy was appointed as the first bishop of the diocese in 1957. On his retirement in 1977, Mar George Punnakkottil was appointed. The Kothamangalam diocese initially encompassed the areas of the current Idukki diocese which was formed in 2002. The diocesan cathedral is St George's Cathedral, located at the High Range Junction. The eparchy covers 12 foranes, with 115 parishes. Kothamangalam is a small town lying on the foothills of the Western Ghats and is referred as “the gateway to the high ranges.” The town is also an important trading center for spices and hill produce.
Kothamangalam is known for its old Christian churches and its prominent educational institutions. St. Thomas is believed to have preached in this place and converted about 240 Brahmin families to the Christian faith.
The diocese enjoys all four seasons. The winter season starts with the end of the northeast monsoons. In the highlands the climate is cool throughout the year, winter temperatures often fall below 10C.
It is surrounded by the archdioceses of Ernakulam and Madurai and the dioceses of Kanjirapally, Palai, Idukki and Coimbatore.