2 - 3 hrs by bus......enjoy ;-)
The Distance between Hamburg and Cologne is 222 miles or 357.2 Kilometers. According to www.raileurope.com, it take 4hrs & 3 minutes to get there on the train.
The distance from frankfurt to hamburg is 307 miles / 494 km
745.74 kilometres (463.38 miles)
366.12 kilometres (227.5 miles)