The book of Leviticus is the third book of the Old Testament, and is concerned with giving instructions and rules to both priests and worshipers. In general, Leviticus indicates that by following these rules mankind becomes closer to God, and by not following them God moves further away.
Leviticus 20:13 is a verse which speaks solely to sexuality not gender:
If a man also lie with mankind, as he lieth with a woman, both of them have committed an abomination: they shall be surely put to death; their blood shall be upon them. (King James Version)
As-written, this is a reasonably clear prohibition against male homosexuality.