A partial oxidation process for the production of a stream of hot clean gas substantially free from particulate matter, alkali metal compounds, hydrogen halides, hydrogen cyanide, sulfur-containing gases, and with or without ammonia for use as synthesis gas, reducing gas, or fuel gas. A pumpable hydrocarbonaceous fuel selected from the group consisting of liquid hydrocarbonaceous fuel or liquid emulsions thereof, an aqueous slurry of petroleum coke, and mixtures thereof and wherein said hydrocarbonaceous fuel contains halides, alkali metal compounds, sulfur, nitrogen and inorganic ash containing components, is reacted in a gasifier by partial oxidation to produce a hot raw gas stream comprising H.sub.2, CO, CO.sub.2, H.sub.2 O, CH.sub.4, NH.sub.3, HCN, HCl, HF, H.sub.2 S, COS, N.sub.2, Ar, particulate matter, vapor phase alkali metal compounds, and molten slag. The hot raw gas stream from the gasifier is cooled in a radiant cooler and cleaned. Optionally, ammonia is removed from the gas stream by being catalytically disproportionated into N.sub.2 and H.sub.2. The process gas stream is cooled and halides and HCN in the gas stream are reacted with a supplementary alkali metal compound to remove HCl, HF and HCN. Alkali metal halides and alkali metal cyanide, vaporized alkali metal compounds and residual fine particulate matter are removed from the gas stream by further cooling and filtering. The sulfur-containing gases in the process gas stream are then reacted at high temperature with a regenerable sulfur-reactive mixed metal oxide sulfur sorbent material to produce a sulfided sorbent material which is then separated from the hot clean purified gas stream having a temperature of at least 1000.degree. F.