Is he fixed? And are you sure he is peeing and not spraying ? When is the last time he was seen by a vet? If he is peeing it could be a UTI . If he is not fixed he most likely spraying . Most vets will tell you once they start spraying their is a good chance they will keep spraying even after they have been fixed. Other wise what I have done with every cat I have ever owned is : every half hour I take them to their box and stand there , if they try to get out I put them back in the box ,waite about 10 min then let them go . It takes about 1 week and is very time consuming , but it has always worked for me. Good luck -ski-