Describes arrangement of apparatus and gives a process for the continuous production, from distillable bituminous fuel, of water gas virtually free from hydrocarbons from subsequent synthesis to hydrocarbons for motor fuel. A gaseous heat carrier comprising a highly heated water gas and steam mixture in cycle is circulated through a gasification step. The distillable fuel is distilled by the heat of the gaseous heat carrier to liberate hydrocarbons from the fuel and is also caused to react with the steam in the heat carrier to form water gas. From the gasification step the carrier goes through a reheating step in which the liberated hydrocarbons in the carrier are caused to react to water gas. The reheated carrier returns to the gasification step. The newly generated water gas flows through the gasification step, together with the heat carrier and with the hydrocarbons distilled off in the gasification step. The final and product water gas is withdrawn from the reheated carrier before it re-enters the gasification step.