In a process for forming a methane-enriched fuel, a hydrocarbon feedstock that includes hydrocarbons having molecular weights greater than that of methane (CH.sub.4) is mixed with an oxidizable gaseous reactant that includes water (H.sub.2O) and is free of molecular oxygen (O.sub.2). The mixture, which has a H.sub.2O/total hydrocarbon (H.sub.2O/C) ratio of less than about 1, is heated to an elevated temperature in the presence of a catalyst to form a methane-enriched pre-reformate product. At least a portion of the feedstock hydrocarbons having molecular weights greater than that of methane is converted to methane (CH.sub.4) in the process.