Abstract: Raw synthesis gas produced by the gasification of coal, heavy oil or similar carbonaceous material is contacted with a reforming catalyst at a temperature in the range between about 1000.degree. and about 1800.degree. F. and at a pressure between about 100 and about 2000 psig prior to adjustment of the carbon monoxide-to-hydrogen ratio and treatment of the gas to increase its B.t.u. content. This catalytic reforming step eliminates C.sub.2 + compounds in the gas which tend to form tarry downstream waste products requiring further treatment, obviates polymerization problems which may otherwise interfere with upgrading of the gas by means of the water gas shift and methanation reactions, and improves overall process thermal efficiency by making possible efficient low level heat recovery.