We provide a clear demonstration of the migratory insertion of methylene into the metal-carbon bond on a silver single-crystal surface. The insertion reaction is characterized by the interaction between methylene and perfluoromethyl groups coadsorbed on Ag(111). The CH2 insertion into the Ag-CF3 bond followed by P-fluoride elimination produces CH2=CB2 which is our experimental evidence for the insertion mechanism. Our observations confirm the step concerning the propagation of the carbon chain in the Fischer-Tropsch processes.