46 In this context, it is a source of joy to note that Catholic ministers are able, in certain particular cases, to administer the Sacraments of the Eucharist, Penance and Anointing of the Sick to Christians who are not in full communion with the Catholic Church but who greatly desire to receive these sacraments, freely request them and manifest the faith which the Catholic Church professes with regard to these sacraments. Conversely, in specific cases and in particular circumstances, Catholics too can request these same sacraments from ministers of Churches in which these sacraments are valid. The conditions for such reciprocal reception have been laid down in specific norms; for the sake of furthering ecumenism these norms must be respected.
Source: Ut Unum Sint (Vatican.va)