There is a train service operated by Deutsche Bahn Intercity-Express that offers hourly service between these two cities with a trip time of around 27 minutes. One of the highlights of using this mode of transportation is that once you arrive in Cologne, you will find roughly the same schedule for trains coming back which makes it quite easy to spend as much or as little time as you would like in the city of Cologne. All the trains on this route depart from the Dusseldorf Hbf. If you are considering making this trip and you would like a hotel close to the station, a great option would be the Hotel Famosa, which is just a few blocks from the station and offers amenities like a 24-hour front desk and minibars in the rooms.