Refer here:
click hereIntroduced as the 41/42 Madras Central - Cochin Harbour terminus express from 1st April, 1966. Until 1977, this train was known as the 'Kerala' express. After the introduction of the Trivandrum-New Delhi Kerala express, this train lost it's name and was simply known as Cochin express.
In the early 90's, it was extended to Alleppey with the numbers 6041/42, and was converted to a superfast from July 13th, 2014.