Coal or similar solid carbonaceous fuels are liquefied by catalytic hydrogenation of coal-liquid hydrocarbon oil slurries with a hydrogen-rich gas. Both the liquid hydrocarbon slurrying oil and the hydrogen-rich gas are derived in the process. Noxious hydrogen-containing purge and vent gases and optionally high ash-containing bottoms from a vacuum fractionator are used as feed to a partial oxidation gas generator to produce synthesis gas from which the hydrogen-rich gas is derived.