Plutonium monocarbide pellets of 93% theoretical density were pressed and sintered from powder that was prepared by crushing arc-melted buttons. Powders with particle sizes of < 74, < 44, and < 15 µm had optimum sintering temperatures of 1400, 1350, and 1250°C, respectively. Additions of up to 4 wt% binder to the powders caused a decrease in the densities and an increase in the carbon contents of the sintered pellets. Metallographic and x-ray diffraction examination and chemical analysis were used to determine some phase relationships in compositions near the monocarbide composition in the Pu-C-O ternary system.