The diocese of Irinjalakuda was established on1978, June 22 bifurcating the then diocese of Trichur and nominated Monsignor James Pazhayattil as the first Bishop who has been serving as Bishop since. The Eparchy of Irinjalakuda covers an area of about 1,180 square kilometers and has at present 43, 301 Catholic families.
The diocese is blessed by the footsteps of St. Thomas the Apostle since it contains Kodungallur which is the cradle of Christianity of India. From the ancient times, Kodungallur was an important trade centre. This center had trade relations with the Persians, Greeks and Romans. According to the tradition, St. Thomas, the Apostle, landed at Kodungallur (Malliankara), the capital of the Chera Empire in the year A.D. 52. He preached the Gospel here for the first time and founded churches. The apostolate of St. Thomas was fruitful among the people of Kerala. According to Malabar tradition seven Christian communities were formed in seven different places before he was martyred in A.D. 72 at Mylapore. Thus, the diocese of Irinjalakuda was privileged to receive the Christian faith for the first time in the history of India.
Malayalam language is in use. English, a mandatory subject in public schools, is widely spoken and understood. Minority speaks Tamil.
The diocese basically enjoys 4 types of climate such as Winter, Summer, South West Monsoon and North East-Monsoon.
The winter season sets in during the month of December and continues till end of February. During this season comparatively there is less rainfall. Winter is followed by the summer season. Its starts in February and continues till May. Occasional showers with lightning is a characteristic of this season. The South West Monsoon begins either in the end of May or in the beginning of June and fades out by September. Moving towards north, this seems to gain intensity. The North East Monsoon commences in October, dry weather setting in by the end of December. The annual range of temperature is comparatively low in Kerala. In the coastal area it is hot and humid during April-May while cool during December-January.
The diocese sprawls from Karuvannur river in the North, to Chalakudy river in the South. West boundary is the Arabian Sea and East boundary being the districts of Palaghat and some parts of Tamilnadu state.