My friend is dying from brain cancer and I want to baptize him. How do I do it?
I am very sorry to hear your friend is dying, and I know your heart is in the right place in your desire to baptize him. Unfortunately, you cannot do so, at least not at this time. The ordinary minister of baptism is a priest or deacon. If your friend wants to be baptized, you can call a priest or deacon on his behalf. Under ordinary circumstances though, you cannot baptize him yourself. The Code of Canon Law states:
If the ordinary minister is absent or impeded, a catechist or some other person deputed to this office by the local ordinary, may lawfully confer baptism; indeed, in a case of necessity, any person who has the requisite intention may do so (canon 861).
An adult in danger of death may be baptized if, with some knowledge of the principal truths of the faith, he or she has in some manner manifested the intention to receive baptism and promises to observe the requirements of the Christian religion (canon 865).
If your friend is able to talk with you about his wishes, I urge you to do so, in as gentle and respectful a manner as possible. If he is not able to do so, you could ask his family if he has ever expressed a desire for baptism—and certainly his family should not be left out of the loop in making any such arrangements for baptism. If either your friend or his family, speaking on his behalf, do not express a desire for baptism, then I believe you should limit yourself to praying for your friend, perhaps using the prayers of the Divine Mercy chaplet.