The Fischer-Tropsch (FT) synthesis on a large scale is of interest, as a means of conversion of remote natural gas to high-quality products, particularly, liquid transportation fuels. Recent developments have resulted in reactors of advanced design having production capacities of 2500 bbl/day or higher, which is more than two orders of magnitude higher than the productivity of classical reactors operated before or during World War II. Some fundamental aspects of these reactors, which belong to the classes of gas-solid fluidised beds, multi-tubular trickle-beds, and slurry bubble columns, are discussed to aid the selection and design of reactors for a specific application. Special attention is given to scaling up of slurry bubble columns. Published experimental work is carefully analysed, and procedures are recommended for the estimation of the necessary design and scale-up parameters. Model calculations of a commercial FT reactor are presented in order to underline various important design and operating issues. (C) 2000 Elsevier Science B.V. All rights reserved.