Sunday School is a very active wing of the St. Thomas Indian Orthodox Cathedral,conducting classes after the Holy Qurbana every Sunday. The classses range from Kindergarten through to Year 10, following the curriculum set by the Orthodox Syrian Sunday School Association of the East. At the end of each year an examination is conducted and the children are rewarded for their efforts with prizes and they progress to the next class.

Apart from the regular curriculum,the students are encouraged to memorise a Biblical verse every Sunday. Songs sung in the Holy Qurbana are practiced to encourage the children's active participation in the Holy Qurbana. Different topics are explained and discussed in the higher classes so that the children attain a clearer and deeper insight into the Orthodox faith and tradition.

Participating in the Christmas and St.Thomas Day celebrations organised by the Church,the children are given the opportunity to exhibit their musical and theatrical talents. Sunday school has sixty eight children on roll,eleven teachers and two relieving teachers.

The following are the list of teachers (in alphabetical order):
Mrs. Wendy Mathews as Head Mistress

Mrs. Anita Varghese,
Mrs. Cynthia Godly
Miss Eleena Varghese
Miss Jaimy Lukose
Mrs. Jessy Abraham
Mrs. Jessy Koshy
Mr. Jini Jose
Mrs. Nysha Thomas
Mrs. Rupa Phillip
Mr. Sam Thomas
Mrs. Sheeba Phillip

The two relieving teachers are Mrs.Lillykutty Varghese and Mrs. Jessy Lukose