Impediments are:
1 Unlawful marriage (Apostles 19, Penthekte 26)
2 Bigamy (Apostles 17, Penthekte 3, Basil 12)
3 Marriage to a widow or divorcee (Apostles 18)
4 Marriage to a non-virgin
5 Marriage to an adultress, eve if she and her lawful husband are separate (Apostles 18)
6 Carnal sin with any person prior to marriage (Neocaesarea 10 says that if a cleric guilty of carnal confesses it "afthormethos" (spontaneously, on his own) after ordination, he is to be prevented from excercising sanctifying authority if a priest. A deacon is made a subdeacon.
7 Loss of good reputation (Laodicea 12, Nicea 9) Canons do not specify what constitutes loss of good reputation. This is left to the discretion of the ordainer).
8 Offense punishable by canons.
Source: by prof. Lewis J. Patsavos The Canon Law of the Orthodox Catholic Church p. 73-74, Boston Massachusets, 1975.
Grigorii