Nanoscale, binary, M-Fe (M double bond Mo, Ni, or Pd) catalysts supported on alumina have been shown to be very effective for the decomposition of undiluted methane to yield hydrogen and multiwalled nanotubes. The same suite of catalysts has been tested for non-oxidative catalytic dehydrogenation of undiluted ethane and propane. After prereduction at 700 degreesC, all three binary catalysts exhibited significantly lower decomposition temperatures and longer time-on-stream performances than either the nonmetallic alumina support or a mono-metallic Fe/alumina catalyst. Ethene, propene, water, and carbon oxides were absent, and only hydrogen, methane, and unreacted ethane or propane were observed in the product stream. The carbon deposit left on the catalyst bed showed two distinct forms, depending on the reaction temperature. Above 600 degreesC, the carbon deposits were in the form of multiwalled nanotubes with some irregularly spaced capping of the innermost walls. At or below 500 degreesC reactor temperature, carbon nanofibers with capped and truncated stacked cone structure were produced.