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

The service of high speed trains between Brussels/Bruxelles and Cologne/Koln is split between
ICE and Thalys trains.
The timetable is arranged so that either one of these types of trains departs in each hour

Final Destination: Paris Nord – the Thalys trains

Final Destination: Bruxelles Midi – the ICE trains

All trains also call at: Aachen and Liege

Most of the ICE trains also call at: Bruxelles-Nord
Note that the Thalys trains do NOT call at Bruxelles-Nord.

Neither the ICE or Thalys trains call at Bruxelles-Centraal.

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

Book early and save: Yes

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.

*= this can be more variable for the Eurostar formerly Thalys trains.
Take care if you will be looking up a journey more than six months ahead of the travel date.
For a few weeks after the six month period the discounted ticket prices can also be available, but the non-discounted tickets can be on sale for dates further ahead.
So if you be will looking up a journey more than six months ahead and only see prices of more than €100, refrain from purchasing and return to the booking service a few weeks later.

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.

Booking Tickets:

What type of train you will be travelling by generally makes little different to the cost of tickets, the popularity of each 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.

When making an online booking, check that you’re looking at booking info for the direct trains.

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.
Use the ‘earlier trains’ and ‘later trains’ buttons to search for the cheapest ticket prices.

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.
DB (the booking site of Germany's national rail operator) tends to offer the lowest prices for the journeys by ICE train.
And DB now also sell tickets for the Eurostar formerly Thalys services; though you will see 'Determine price' listed on the DB website for Thalys departures

Seat Reservations:

Seats will automatically be assigned when booking any ticket for the Eurostar formerly Thalys trains.

For ticket holders seat reservations are always optional on the ICE trains route, but if you will be using a rail pass they are now mandatory when travelling between mid-June and mid-August - check the Train guide for the exact dates.
Regardless of whether you will be using tickets or rail passes they cost €4.90 when travelling in 2nd Class and €5.90 when travelling in 1st class.
They are included within the cost of booking 1st class Flexpreis tickets and both 1st and 2nd class Flexpreis Plus tickets.
Specific seats can be selected from seating plans - you don't have to accept the seat(s) that you will be automatically offered.

When booking Super Sparpreis, Sparpreis and 2nd class Flexpreis 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 and your journey involves more than one train, you will then have to pay for separate reservations per train.
Specific seats can be selected from seating plans - you don't have to accept the seat(s) that you will be automatically offered.
So take that into account when comparing the cheapest prices of 1st and 2nd class tickets on the ICE and Thalys trains.

For travel on the ICE trains, they are only included within the cost of booking 1st class Flexpreis Europa tickets and both 1st and 2nd class Flexpreis Plus Europa tickets.

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.

Some ticket agents will automatically include the reservation fee for the ICE train, even though it's optional (you can choose to remove it); on other agents including DB, the initial 2nd class price you see won't include the seat reservation charge.

Using rail passes:

If you will be travelling from Cologne/Koln to Bruxelles to with a valid Eurail or InterRail 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 of €5.30 in 1st class and €.4 in 2nd class are relatively expensive for such a comparatively short journey.
In contrast the rail pass reservation fees for the Thalys trains will be €30 in 1st class and €20 in 2nd class.