Reciting Kaddish for a non-relative

On the Air with Rav Aviner - Shut Radio

Q: Is it permissible to recite Kaddish for someone who is not a relative.
A: There is no obligation but it is permissible and certainly a great mitzvah. If your parents are still living, you must ask permission from them to recite Mourner's Kaddish for someone else. You do not need to ask permission to recite Kaddish De-Rabbanan, since it is not a Kaddish for the deceased but over Torah learning.