Giveaway Keys already activated?

I have a few keys already activated on my account,i.e. Company of Hereos (on the LINKS section on the games page on steam it shows me the CD Key), that I want to give away because I no longer play them.

Are these redeemable by others if I give them out? I don't want these games anymore and want to give them away to people who have not played them yet. I'm assuming it will activate them on their end and just remove them from my library?

Update: Got it, thank you!