When attempting to get an adult cat to use a litter box, little training is required. Using a litter box is a natural instinct for an adult cat. The key to training her to use the litter box is to provide the right environment. If you introduce the cat to the litter box properly and provide her with a clean box she can access without obstacles, she should use the box without exception.
Select a litter box large enough for the cat. It should be long enough for his entire body to fit into it and wide enough for him to turn around. A plastic box is best because it is non-absorbent and easy to clean.
Limit the cat’s access to one room of the house for the first few days. A small room, such as a bathroom, is a good location. The room should be low-traffic and quiet. The cat’s litter box, food and water should be available in the room. The litter box should be placed at the opposite end of the room from the food and water.
Pour unscented, clumping litter into the box. Most cats seem to prefer this type of litter.
Place the cat in the litter box to ensure she knows where it is located.
Go into the room often to socialize with the cat. Each time you go into the room, scoop the cat’s box. The cleaner you keep the box, the more likely it is that your cat will use it.
Release the cat into the rest of the house when you feel he is comfortable with the new surroundings and is consistently using the litter box. The door to the cat’s room should be opened and he should be allowed to leave the room and explore the rest of the house as he chooses. Don’t force the cat to go into other parts of the house until he chooses to do so.