A process for the endothermic gasification of solid carbon in an entrained bed facility comprises partial oxidation of fuel(s) and endothermic gasification of solid carbon, preferably preceded by low temperature carbonization such that the carbonization gas is passed to the partial oxidation and the carbonization coke is passed to the endothermic gasification. The hot gas streaming downwardly from the combustion chamber is deflected to produce separation of the liquid slag and is then passed to the endothermic gasification that operates with a rising gas stream and with addition of solid carbon having a grain diameter of up to 20 mm. The speed of the gas at the carbon inlet is higher than, and the speed of the gas at the end of the endothermic gasification is lower than, the suspension rate of the reactive carbon particles, to produce an increase of the relative speed difference between the gas and the carbon particles. Apparatus is also disclosed for carrying out the process.