No you can't.

No.

You can't redeem them on steam. But you could use the steam feature to add a "non steam" game, and so it would show up on your steam library, and you could still have the steam interface in game.

Welcome to GOG!

For future reference, GOG is a direct competitor of Steam and therefore does not provide Steam keys for any of the products they sell and never will. Additionally, Steam is considered by many to be a form of DRM, which is a dirty word around here. GOG and its parent company, CDProjekt, are vehemently opposed to DRM of any kind, so providing keys to tie your GOG-bought, DRM free games to an outside DRM scheme goes against the core philosophy on which this site was founded. If you just want to use Steam to manage your library of games and for it's additional social features, you can do as Grazor suggested and add the games as non-Steam shortcuts in the Steam client (a lot of us do that), but downloading, updating and installing the game is always going to be a manual process, just like in the old pre-Steam days.

Sure having a game be DRM free is a nice option but to take away every other option is just restricting freedom. I thought that the entire point of DRM free games was to GIVE freedom? So what if I want to redeem GOG games on Steam? They got my money. It's quite clear that THIS is the only reason reason why they don't allow DRM redeemable keys. Not the self-righteous BS you're spewing afterwards.

Excuse me? Almost two years ago I post a helpful and friendly response to a new GOG member with legitimate concerns and you choose now to respond with an insult to me and GOG? What is wrong with you? Is your life so empty that you have to go trolling years old forum threads for opportunities to share your ignorance with the world? Get a life.

You do have a freedom to buy the game wherever you want, so cut the crap. It's not like you pay for your burger at mc donald's and decide to redeem it at burger king either.

Actually, the Fallout version of Gog is from Interplay meanwhile the one in Steam (And their serial keys) are from Bethesda, that is the same reason GOG can't sell them anymore.
Similar to Origin, GOG give certain interoperability with specific games with Steam (AKA: The Witcher's games) , and in the end how universal is a Serial Key is under control of the developers, not the companies who distribute them (THOUGH they have power in that choice).

Edit: Ok, I need to rest, didn't see I just help to necromancer an old topic :(

With the Witcher games, if you bought it at retail or bought it originally on Steam, GOG does allow you to register the game on GOG as well as Steam. However, that is because originally, retail and Steam were the only ways to get those games as GOG did not sell modern titles. After Witcher 2, that changed. No other titles from GOG have any kind of cross service functionality.*

Don't worry about the necro participation, at least your post was relevant discussion. ;)

*I should say no others that I am aware of. At the time of the thread's original posting, this was entirely true, but with all the changes GOG has made, it's possible that isn't the case anymore.

Sorry for continuing to revive an old thread, but it was precisely the recent posts that I wanted to ask about, the witcher games are currently on sale on gog so I was thinking about buying them, however I wanted them for steam, now looking around I quickly found out that you cannot redeem gog games on steam, but according to this the witcher game are an exception?
So, could I buy the witcher games while they are on sale on gog and then redeem them on steam? Or is this no longer the case? Mind you, just to clarify, I dont mean just adding them to the library, but redeeming them like a game bought from humble store for example.

No, would be in the contrary, or at least I think that.
I bought the physical retail and then redeemed them to Gog years later.
There are/were some games that you could to redeemed to Steam accord to their serial keys (similar case is Origins), but I don't know if The Witcher is one of them.

No, it's the other way around: if you bought the Witcher games somewhere other than GOG (retail or Steam) you can redeem them in here and add them to your GOG library.

If you buy them on GOG you can't get Steam keys out of it.

Oh I see, thats too bad, thank you both for the answer though, much obliged.

Unfortunately, The Witcher games can't be redeemed on Steam. You can do it the other way around because CD Projekt Red and GOG are two divisions of the same company.