[en] The role of the surface CH₂ species in the conversion of CO and H₂ to hydrocarbons is used to evaluate the correctness of the Fischer-Tropsch, Pichler-Schultz, and the Anderson-Emmett schemes. CH₂N₂ was used to add CH₂ groups to the cobalt catalyst surface; this resulted in an increased production of higher molecular weight molecules as predicted only by the Fischer-Tropsch scheme. Distributions of ¹³C atoms in the propene formed when a mixture of ¹³CO, H₂, and ¹²CH₂N₂ were passed over the catalyst, also confirmed the Fischer-Tropsch scheme