Self-Baptism Is Not Possible
Q: Can a person baptize himself if there is no one else available to do it, and if not, why not?
A: No one can baptize himself. Self-baptisms (also known as “auto-baptisms”) are automatically invalid, and anyone who was initially baptized in this way would have to be baptized (unconditionally) by someone else (Denzinger 413 [DS 788]).
Another person must be involved to administer the sacrament to symbolize the fact that the person cannot reach up to God and bring down his grace upon himself. God’s grace is something which must be given to a person; it cannot be taken from God.
However, for those in situations where no one is available who is willing to baptize a person, God will not hold this against him, but will count his desire for baptism in place of the baptism itself and give him the grace anyway. This is because God loves us and wants us to have his grace, even when the normal method of communicating it is unavailable.
Thus God wants the communication of his grace properly symbolized (in the normal rite by which it is communicated) but wants it to be communicated even when this symbolism is not possible (when the normal rite is not available). Thus the Council of Trent taught that “justification . . . cannot be effected except through the laver of regeneration or a desire for it” (Decree on Justification 4).