Abstract: A portable cat litter box adjustably mountable on a toilet bowl is provided with the litter box equipped with a trap door and trap door opening mechanism for dumping litter from the box directly into a toilet bowl for ease of litter disposal. A pull member connected to the trap door is moveable from a forward trap door closed position to a pulled out trap door opened position tilted downward from a rear pivot mount structure. Opposite side slotted cam guide structure for the trap door opening and closing are mounted on the bottom of the cat litter box with rod segments mounted on a back and forth trap door movement structure and extended into the oposite side cam guides.