CH4 homologation can proceed under reductive conditions by successive exposures of various supported metals to CH4 and H-2. When a Pt/SiO2 catalyst is submitted to a CO dose after an exposure to CH4 at a moderate temperature, several hydrocarbons are released with a large proportion of olefins. It may therefore be concluded that C-C bonding processes take place during the mere exposure of platinum to CH4 at moderate temperatures.