Ultrasmall and uniform Pd₆Co nanocrystals were deposited on 3D graphene by a facile one-pot surfactant-free route for a catalyst toward formic acid oxidation, showing a much higher electrocatalytic activity, larger peak current density and better stability than Pd/3DG, Pd/C as well as commercial Pd–C, and thus offering great potential for an efficient anode catalyst toward high performance direct formic acid fuel cells.