Brussels to Koeln, Germany
 

We will be arriving in Brussels and taking the train immediately to Koeln (Cologne). Does anyone know if you can buy the train tickets at the Brussels airport to Koeln for the whole trip? I am assuming there are ticket offices in the Brussels airport but didn't want to be surprised if my assumptions are incorrect.

Thanks.

Yes, you should be able to buy your ticket at the airport ticket window. You'll simply have to change in Brussels itself which is about a 20-minute rail ride from the airport. Make certain you know which rail station in Brussels your connection to Cologne leaves from.

Re ticket: depends on which kind of train you are going to take!
If you plan to take the high speed Thalys (journey 2 hrs. 21 min., no changes) you will have to make a reservation in advance!
If you take the intercity express (journey 2 hrs. 30 min., 0 changes) you can just go to the ticket counter at Brussels airport. Unfortunately this train only runs 3x a day (at 6.16, 12.16 and 18.16).
Another alternative without reservation is the slow intercity (3 hrs. 50 min. (!!), 2 changes).
You will always have to travel from the airport to Brussels Midi (Brussel Zuid) first. All the trains to Cologne leave from there.

You can "walk up" and get tickets for Thalys service tickets IF there is space available. If you feel you must use a particular Thalys and to be certain you'll get space on it then yes, you will have to do so before you arrive.

I'm not comfortable making a reservation in advance since you never know when the airplanes will actually land and how quickly you can get through customs. I guess we'll just take our luck with getting on the next available train. Thanks for the responses.

Actually, you can't *always* buy a ticket to Koeln from the Brussels airport. I have gone to the airport from time to time and the train office was only selling tickets to Brussels or other trains that serve the airport. No explanation was given.
Kitty, to get to the train office in the airport from the arrival level, head over to the banks of elevators. Either take them down to the bottom level or take the escalators (if your luggage is small). There are signs for the trains. FYI, there are two tracks that the trains leave from, one on either side of the ticket window. Make sure you know which one the next train is leaving from...

If you buy your ticket at Brussels Midi (Zuid), go into the international ticket office (right next to the round info kiosk). Get a number from the little machines at the entrance (the number you get depends on which international train you plan to take, i.e., Thalys, Eurostar, etc., and when you plan to leave, i.e. immediately or on a different day. It will also tell you which section of the ticket booth to wait in (B,C,D). It's pretty simple and the lines move pretty quickly. Unless you're arriving on a major holiday, you should have no problem getting a ticket for the next train. Remember, that there are two kinds of high speed trains serving Koeln from Brussels--the Thalys, which Myrian mentioned, and also German ICE trains. I have been *told* that a seat reservation is not compulsory for the ICE trains, but I always get one anyway...if you're going first class on the Thalys, you will get a complimentary light snack and beverage served at your seat. With ICE trains, you can get service at your seat, but you pay for it.

A few things about Koeln train station. There is a first class passengers lounge which has nice bathrooms, decent chairs, free coffee, soft drinks, newspapers, tvs showing CNN, etc. You can get there by stairs from the Reise Centrum in the train station (where people buy tickets). There is an elevator in the travel center, but it's been broken for months. To avoid dragging your luggage up the stairs, head over to the elevator for track 1. Take the elevator up to the track and buzz at the lounge entrance (it's the back entrance). Helpful if you arrive at the station and want to freshen up a little before heading on.
BTilke (Brussels)