Using　physical　mixtures　of　Pd/SWNTs　(Pd　nanoparticles　on　single-walled　carbon　nanotubes)　and　Pt/SWNTs,　the　composites　show　electro-catalytic　properties　comparable　to　the　corresponding　alloys:　electron　exchange　readily　occurs　between　the　two　metal　nanoparticles　via　SWNT　support　at　long　ranges　without　direct　atomic　contact,　which　is　responsible　for　the　tunable　alloy-like　properties.