A 5-year-old, castrated male, domestic shorthair cat presented with firm swelling in the right temporal region of the skull. The cat's jaws were almost locked in the closed position. Radiographs showed a mass with an irregular mineralized matrix superimposed on the caudal right mandible and temporomandibular joint. Surgical exploration revealed that the mass arose from the proximal part of the vertical ramus, which was removed, with the exclusion of the temporomandibular joint. It was possible to open the cat's mouth to nearly normal extension immediately after surgery. Recovery was uneventful - the cat has had no problem eating and no mass recurrence has been detected 3 years after surgery. Histological examination of the mass was consistent with chondroma. To the best of our knowledge, this is the first clinical and pathological description of a chondroma in cats, and one of the rare cases describing clinical presentation and management of primary bone tumours involving the vertical ramus of the feline mandible.