United Kingdom and Ireland
Hey Arnold! is sometimes repeated on the Nicktoons channel on Sky channel 606 (and replay channel 630), Virgin Media channel 717, Smallworld Cable channel 606, UPC Ireland channel 606 and TalkTalk TV channel 320.
As of August 2012, it only airs on Teennick. Here is the schedule for what times it comes on Teennick: Friday Nights at 12 & 12:30AM, and 2 & 2:30AM (repeats of 12 & 12:30AM) Saturday Nights at 1 & 1:30AM, and 3 & 3:30AM (repeats of 1 & 1:30AM) Tuesday Nights at 1 & 1:30AM, and 3 & 3:30AM (repeats of 1 & 1:30AM)
You can also buy the season sets and volumes on DVD from various web sites.