Abstract The effects of catalyst calcination conditions, such as calcination temperature and calcination atmosphere composition on the dispersion of cobalt particles over Co/γ-Al₂O₃ catalysts for Fischer–Tropsch conversion of synthesis gas are studied. A number of catalysts were prepared by incipient wetness impregnation of 20-wt% of cobalt onto γ-Al₂O₃ and promoted with 0.5 wt% ruthenium, rhenium, and rhodium. Metal dispersions of active metals were studied by chemisorption of carbon monoxide. The highest dispersion for Co/γ-Al₂O₃ catalyst was achieved by calcination at 400 °C in a flow of N₂. Co metal dispersion seem to be increased in the calcination steps if a flowing gas was used instead of static calcination conditions. The addition of promoter metals like Ru, Re or Rh enhances the dispersion of the active metal.