I have an older rescued male cat that always used litter box with no problem, until I got a kitten about 8 months ago. He will poop in box but urinates on the floor or wherever it lands. They are both neutered males and get along extremely well. Anything I can do??

Give them each their own litterbox. That will solve the problem. The older cat probably doesn't like the scent of the younger one. That will change in time but if it is a problem now. Take the pressure of you and do as suggested. Simple.

That is a great suggestion, I almost posted it myself, but then I thought, how the heck do you make them use only the one you want them to?

Not related, but, we went on a 2 day trip and left our cat home with plenty of food and water for the short time we were away. We also put down two litter boxes, even though it was only for 2 days.

When we got home, I was shocked to see that she had done all her number one in one box, and all her number 2 in the other, without ever mixing her duty in either box.

Seemed very unusual to me.