Church goers normally go to Myeongdong Cathedral for mass, since it is easily accessible, known to many tourists, located in shopping area, visible on blogs and websites.
Last February, I’ve been to Yakhyeon Church, but there is no formal mass and no English mass.
This October, we have visited Yeoksam Catholic Church - Roman Catholic.
Yeoksam Catholic Church - Roman Catholic
Where: Yeoksam-dong 722-9, Kangnam-gu, Seoul, Korea 02-553-0801.
How to go there: Line #2 (green line) Yeoksam Station, Exit 1
Mass Schedule: English Mass on Sundays 9:00 at Basement 2 (KyungHwan-dang Chapel)
The main church holds Korean mass. Ask around or go to basement 2 and find the main door (KyungHwan-dang Chapel) for the English mass at around 9:00-9:30am Sundays.
Below is the list of other English Catholic Mass around Seoul.
Forum discussion posted on: http://www.tripadvisor.com.ph/ShowTopic-g294197-i8161-k7914889-English_Catholic_Mass_in_Seoul-Seoul.html
There is another English mass at Sogang University on Sun. 7:30 P.M at subway DaeHeung station line 6