The isothermal, non-oxidative, two-step conversion of CH4 to C2+ hydrocarbons was investigated over unsupported and supported Pt and Ru catalysts at moderate temperatures and elevated pressures. The single-cycle specific activity (mu mol C2+/g(cat)) and total product yield (mu mol C2+/mu mol surface metal) for Ru powder at 430 K were significantly higher than for Pt powder at 503 K. The activity and total product yield for mixed metal oxide (MMO)-supported Ru were significantly less than for Ru powder; however, Pt/MMO exhibited similar activity and product yield in comparison to Pt powder. The formation of methylbutane and methylpentane increased with increasing pressure over Ru/MMO. However, increasing pressure favored the formation of C-4 species over Pt/MMO.