The gasification of solid carbonaceous materials such as coal is achieved by directing a stream containing the carbonaceous materials onto a high temperature hot spot which has been formed on the surface of a bath of molten iron by oxygen jets blown thereagainst, the stream containing the carbonaceous materials emanating from a non-submerged, top-blowing lance, the oxygen jets emanating from the same lance or from different lances, and the bath of molten iron being contained in a reactor such that its total volume remains essentially constant.