Studies have been conducted on the effect of preparation variables on the activity of coprecipitated cobalt-alumina catalysts to be used for the production of C-1-C-4 hydrocarbons by CO hydrogenation. The preparation parameters considered were the precipitation pH, the precipitation agent, the metal loading, the reduction temperature and the reduction period. It was found that changing pH precipitation with a constant final pH between 11.0 and 12.5 and the use of NaOH together with nitrates as precursors yielded better catalysts with maximal metal surface area. The optimum cobalt loading for the selective production of C-1-C-4 hydrocarbons is around 35 wt%. Optimum activity and selectivity are obtained by applying an 8-h reduction scheme at 648 K under 100 cm(3) min(-1) hydrogen. Calcination prior to reduction has a detrimental effect on metal surface area and hence on catalytic activity.