The conversion of carbon monoxide with hydrogen was studied on a standard Os on SiO2 catalyst at different reaction temperatures, in the range between 200 and 300 °C. Additionally, supported di- and triatomic organometallic Os complexes were tested for their activity in the Fischer-Tropsch synthesis at 220 °C. All compounds showed formation of hydrocarbons, indicating that the organoosmium complexes are indeed active for C─C bond formation. Osmium as Fischer-Tropsch catalyst, however, is approximately 100 times less active compared to ruthenium. Very high methane selectivities (> 90 C-%) were obtained as well as high olefin to paraffin ratios, in particular with the organometallic complexes tested.