found this at
catholicherald.com/saunders/04ws/ws040506.htm
don’t know if it helps
Can Catholics receive communion in a Protestant Church or
vice versa? Vatican Council II recognized that the Protestant Churches “have not preserved the proper reality of the Eucharistic Mystery in its fullness, especially because of the absence of the Sacrament of Holy Orders” (
Decree on Ecumenism, No. 22). For this very reason, the sharing of Holy Communion between Protestants and Catholics is not possible
(Catechism, No. 1400). This statement does not suggest that Protestant Churches do not commemorate the Lord’s death and resurrection in their communion service or believe that it signifies a communion with Christ. Nevertheless, Protestant theology differs with Catholic theology concerning the Holy Eucharist over the real presence of Christ, transubstantiation, the sacrifice of the Mass, and the nature of the priesthood. For this reason, Protestants, although perhaps upright Christians, may not receive Holy Communion at Mass, and Catholics may not receive communion at a Protestant service.
Our Holy Father in his beautiful encyclical, *The Eucharist in its Relationship to the Church *(
Ecclesia de Eucharistia) taught, “The Catholic faithful, while respecting the religious convictions of these separated brethren, must refrain from receiving the communion distributed in their celebrations, so as not to condone an ambiguity about the nature of the Eucharist and, consequently, to fail in their duty to bear clear witness to the truth. This would result in slowing the progress being made towards full visible unity. Similarly, it is unthinkable to substitute for Sunday Mass ecumenical celebrations of the word or services of common prayer with Christians from the aforementioned Ecclesial Communities, or even participation in their own liturgical services. Such celebrations and services, however praiseworthy in certain situations, prepare for the goal of full communion, including Eucharistic communion, but they cannot replace it” (No. 30). Objectively speaking, to knowingly violate these precepts by receiving communion in a Protestant Church or neglecting to worship at Mass constitutes a mortal sin.