Hi,
Deacons have never been able to celebrate Mass. Only priests can celebrate Mass. Deacons may assist the priest by reading the Gospel and even by preaching the homily. If they could celebrate the Mass, they would be priests and not deacons.
Those who are studying for the priesthood are eventually ordained deacons. But they are called transitional deacons because after a period of time they are ordained to the priesthood. Permanent deacons can be married, but remain deacons.
Fr. Vincent Serpa, O.P.
