Catholics May Not Be Godparents of a Non-Catholic

Directory for Principles and Norms of Ecumenism:

98. It is the Catholic understanding that godparents, in a liturgical and canonical sense, should themselves be members of the Church or ecclesial community in which the baptism is being celebrated. They do not merely undertake a responsibility for the Christian education of the person being baptized (or confirmed) as a relation or friend; they are also there as representatives of a community of faith, standing as guarantees of the candidate’s faith and desire for ecclesial communion.

a) However, based on the common baptism and because of ties of blood or friendship, a baptized person who belongs to another ecclesial community may be admitted as a witness to the baptism, but only together with a Catholic godparent. A Catholic may do the same for a person being baptized in another ecclesial community.