The previous posters are right-on with their suggestions and advice.
I always say rule out medical issues first. Would be awful to treat it as behavioral and then find out the cat is sick.
Males can block pretty easily from UTI's that get advanced to crystals.

After the vet check, DO clean the areas with the appropriate enzymatic cleaners such as Nature's Miracle, made specificly for cleaning cat urine odors. I'd also second the Feliway. I used both the plug-ins and the spray to stop a cat who was marking because of behavioral issues.

I've also been through the heartbreaking problem of a cat who had sterile cystitis due to stress of living in a multi-cat household. We did everything we could from the medical end and the behavioral and environmental end but had to ultimately re-home her so she would be completely happy and healthy in an only cat home. It was the hardest thing to do but it was the right thing and she is quite healthy and happy now, for which I am very thankful.

The posters who mention that what could stress the cat into inappropriate urination may seem very insignificant to you are quite correct. My vet has a cat who stresses each and every time she removes the litter box to clean it and if she doesn't put it back in the exact same spot, the cat will urinate on the floor where the box should be.

But, it really is very important to have a vet check and a spin test of the urine done. Ask for a copy of the urinalysis and research it. UTI issues are not always an easy cure unfortunately.

I hope your kitty will be fine and if it is a UTI that it's a simple one that will respond well to antibiotics. Good luck.