Who Can Baptize?
The ordinary ministers of Baptism are the bishop and priest and, in the latin church, also the deacon. In case of necessity, anyone, even a non-batpized person, with the required intention, can baptise, by using the Trinitarian baptismal formula. The intention required is to will to do what the Church does when she baptises. The church finds the reason for this possibility in the universal saving will of God and the necessity of Baptism for salvation.
Source: Para 1256, Catechism of the Catholic Church, 2nd Edition, Libreria Editrice Vaticana, 24th Printing, January 2013