In addition to the active metal (usually Fe or Co), two other components comprise the catalyst: promoters and the catalyst support.  Promoters are additives that enhance the behavior of the catalyst. For F-T catalysts, typical promoters including potassium and copper, which are usually added as salts. The choice of promoters depends on the primary metal, iron vs cobalt. Iron catalysts need alkali promotion to attain high activity and stability (e.g. 0.5 wt% ). Potassium-doped α-FeO are synthesized under variable calcination temperatures (400–800 °C). Addition of Cu for reduction promotion, addition of ,  for structural promotion and maybe some manganese can be applied for selectivity control (e.g. high olefinicity). The choice of promoters depends on the primary metal, i.e., iron vs cobalt. While group 1 alkali metals (e.g., potassium), help iron catalysts, they poison cobalt catalysts.
Catalysts are supported on high-surface-area binders/supports such as silica, alumina, or zeolites.