A process for producing liquid and, optionally, gaseous products from gaseous reactants includes feeding at a low level a gaseous reactants feed comprising at least CO and H2 into an expanded slurry bed of solid non-shifting hydrocarbon synthesis catalyst particles suspended in a suspension liquid, the expanded slurry bed having an aspect ratio of less than 5. The gaseous reactants and any recycled gas are allowed to react with a per pass CO plus H2 conversion of at least 60% as they pass upwardly through the slurry bed at a gas velocity of at least 35 cm/s, thereby to form liquid and, optionally, gaseous products, and with the gaseous reactants and any recycled gas and any gaseous product assisting in maintaining the solid catalyst particles in suspension in the suspension liquid, and with the liquid product forming together with the suspension liquid, a liquid phase of the slurry bed.