Ochroconis gallopavum was identified as the causal agent of fatal encephalitis in a young, short-hair, domestic cat. The cat initially developed an ulcerated mass on the left side of the tongue and signs of pain in the abdomen. The tongue lesion was surgically removed and exploratory abdominal surgery revealed abnormalities suggestive of pancreatitis and peritonitis. During the month after surgery, the cat's health declined, manifested by sluggishness, loss of appetite and abnormal behaviour. Following a final rapid deterioration, the cat became non-responsive and was euthanized. Histologic examination of the brain, lung and mediastinal lymph node lesions revealed large numbers of pigmented, septate, branched, hyphal elements with swollen intercalary and terminal vesicles, and short chains of moniliform hyphal cells. Cultures of the mediastinal lymph nodes yielded a dematiaceous, thermotolerant fungus that was identified as O. gallopavum. This report describes the first well-documented infection in a cat caused by O. gallopavum.