How to take the rail journey from Brussels/Bruxelles to Cologne/Köln

A choice of train services:

The service of high speed trains between Brussels/Bruxelles and Cologne/Koln is split between ICE trains and Eurostar (formerly Thalys) trains.
The timetable is typically arranged so that either one of these types of trains departs in each hour between 09:00 and 18:30, the service alternates - but the service is more sporadic either side of these times.

What type of train service you will be travelling by generally makes little different to the cost of tickets, the popularity of each specific departure has a bigger impact on prices.
The tickets for the ICE trains are made available two months ahead of the Eurostar (formerly Thalys) trains, so the very cheapest tickets for the ICE trains can have sold out before the Eurostar (formerly Thalys) tickets have been placed on sale.

Though something to look out for if you would prefer to travel in a reserved seat is that the reservations are complimentary on the Eurostar (formerly Thalys) trains are complimentary, while on the ICE trains they're optional and therefore have an additional cost.
Because seat reservations aren't mandatory on the ICE train, travelling by them is a cheaper option when travelling with Eurail or InterRail passes.

The ICE trains travel at the same speed as the Eurostar (formerly Thalys) trains, most of the ICE trains are around 4 mins slower than the Eurostar (formerly Thalys) trains due to their additional station call at Bruxelles-Nord.

Departing from Bruxelles-Midi/Brussel-Zuid station:

Aim to be at Bruxelles Midi/Zuid station a minimum of 15 - 20 mins before your train is due to depart.
You will usually have to pass through security checks before boarding these trains and queues can build up at busy times.

The security checks are at the entrance to voies (platforms/tracks/3 -6) and these ICE and Eurostar (formerly Thalys) trains to Koln are usually scheduled to depart from this part of the station.
But check the departure screens before heading for the security checks, these trains can occasionally be scheduled to leave from voies (platforms/tracks) 7 or 8.

If you'll be commencing your journey in a location convenient to Bruxelles-Central station, you'll have a faster end-to-end journey if you take the ICE trains.
Taking a train from Bruxelles-Central to Bruxelles-Nord and joining the ICE trains at that station will save around 20 minutes compared to heading to Bruxelles-Midi in order to board a Eurostar (formerly Thalys) train; and the Thalys trains don't call at Bruxelles-Nord.

Trains departing at different times can be cheaper than others leaving on the same day, so you may need to look through the day's departures to find the cheapest fares.
It can also be worth comparing the prices across the agents, particularly if you want to take a specific trains, as there can be variations in price.

When travelling from Bruxelles/Brussels to Koln/Cologneby train, some journey options involve taking an ICE train while others involve taking a Eurostar (formerly Thalys) train between these two cities.
This impacts on booking tickets.

Taking the ICE trains:

All of the tickets agents sell the journey options which involve taking this combination of trains.

Online bookings open: up to 6 months ahead of the travel date
This booking period tends to be shorter when looking up journeys between mid August and mid October.

Three types of tickets are always available: Sparpreis Europa and Super Sparpreis Europa and Flexpreis Europa.

A key difference between these types of tickets is refunds:

• Super Sparpreis tickets are cheapest, but they can't be refunded at all.
• Sparpreis tickets can be refunded for a fee, but the refund will be in the form of travel vouchers to be used for alternative / future journeys.
• Flexpreis tickets can be refunded at no additional charge.

The other key difference is that both types of Sparpreis tickets are only valid on the specific departures selected when booking, but the Flexpreis tickets live up to their name, as they can be used on any departure on your travel date.

Note that none of the tickets can be exchanged to a different departure.
There's no need for this to be available for Flexpreis tickets, as they aren't train departure specific.
If you book a Sparpreis ticket and want to travel by a different departure you can refund it and then use the travel voucher towards the cost of the new booking.
Super Sparpreis tickets can't be exchanged or refunded.

The Sparpreis and Flexpreis tickets also include 'City tickets' for Koln which can be used on public transport on from Koln Hbf,

Seat reservations:
Seat reservations are optional on the ICE trains on this route - take note if you will be using a rail pass.
They cost €4.90 when travelling in 2nd Class and €5.90 when travelling in 1st class and the fees will cover both ICE trains
Specific seats can be selected from seating plans - you don't have to accept the seat(s) that you will be automatically offered.

They are included within the cost of booking 1st class Flexpreis Europa tickets and both 1st and 2nd class Flexpreis Plus Europa tickets.
Though despite seats being automatically assigned when booking these three types of ticket - and these tickets being valid on any departure, you will need to pay to re-book the reservations, if you subsequently decide to travel on an alternative train.
So because you won't save by booking these types of tickets in advance, it can be a good idea to wait until you are sure when you will want to travel.

When booking Super Sparpreis Europa, Sparpreis Europa and 2nd class Flexpreis Europa tickets, you have the option of purchasing seat reservations later.
It can be worth re-looking up a journey a week or two ahead of travel, because the DB website will indicate how busy a departure will be.
Although if you do book your reservations later you will then have to pay for separate reservations per train.

Booking on the DB website:
If you can be flexible with your departure time use the 'best prices' tool - at the top right on the list of journey options.

Taking a Eurostar (formerly Thalys) train:

Bookings open: 4 months ahead of the travel date (usually)

B-Europe and Save A Train are seemingly the only ticket agents which sell this combination of trains.
Note that tickets can't be booked on the Eurostar website.

Eurostar (formerly Thalys) ticket terms summary:
'Tickets for travel in Standard and Comfort Class can be can exchanged without paying an exchange fee, as long as tickets are exchanged 7 days or more before the departure time of their individual journey.
Though if the new ticket option is more expensive the difference in price will need to be paid, but if it is cheaper the price difference won't be refunded.
But make the exchange within 7 days of the individual journey and an admin fee of €15 will need to be paid, along with the price difference
Though tickets can be refunded up until 7 days before departure, but are non refundable in the 7 days before departure.
So note that the cheaper tickets to travel by the Thalys trains can be refunded (up until 7 days), but the cheaper tickets for the ICE trains can't.
Tickets for travel in Premium Class are exchangeable without payment of an admin fee up to the departure time, but price difference between the old and new tickets will need to be paid.
Premium Class tickets can up refunded until one hour after the departure time'.

Seat Reservations:
Your seats will automatically be reserved on the Eurostar (formerly Thalys) trains.

Using rail passes:

If you will be travelling from Bruxelles to Koln with a 1st or 2nd class rail pass, target the ICE trains.

You won't have to pay any rail pass reservation fees to travel by those trains; though the optional fees are €5.90 in 1st class and €.4.90 in
In contrast the rail pass reservation fees for the Thalys trains will be €30 in 1st class and €20 in 2nd class.