The Catechism of the Catholic Church tells us, “In case of necessity, any person, even someone not baptized, can baptize, if he has the required intention.  The intention required is to will to do what the Church does when she baptizes" (Catechism of the Catholic Church, #1256). 

Baptism must be administered by pouring the water three times over the head of the one being baptized while saying, "(Name), I baptize you in the name of the Father, and of the Son, and of the Holy Spirit."