Marie 25; It could be that he is using the hall way because he doesn't like, or is not comfortable with the present location of the other cat's litter box. I'd place a larger litter box in the hall way where he is pooping. I have the same problem with Little Bit ( a tiny silver/tan tortie). She will not use any one of 3 litter boxes around the house, but will continually poop next to them. (At least she is in the correct area!) Try this first, even if you use a temporary box, such as a beer, 24-can flat, something to see if he will use it.

...............wayne