Solid fuels are gasified in a fixed bed with gasifying agents passed through the fixed bed from below. The gasification residues are withdrawn as solid ash or as liquid slag under the fixed bed. The reactor is charged with solid fuels through a lock chamber and with tar through a supply conduit. The tar is delivered to the fuel in numerous individual streams, which are distributed over the cross-section of the fixed bed.In the gasifying reactor, an inclined distributor surface is disposed over the fixed bed and has numerous passage openings for the tar and the solid fuels. The outlet end of the tar supply conduit is directed to the upper portion of the distributor surface. A tar tub having outlet openings is associated with the distributor surface and serves to receive the tar. The distributor surface is rotatable on a vertical axis.