Ultrafine and highly dispersed PdCu nanoalloys anchored on porous carbon were synthesized by a facile NaBH4 reduction method in a ionic liquid (IL)/water solution system. During the synthesis, the IL solvent can act not only as a stabilizer to slow down the particle growth and prevent the agglomeration, but also as a functional agent to improve the hydrophilicity and sorption property of carbon support due to the functional groups. The resulting PdCu/porous carbon (PdCu/PC) exhibits a remarkable activity for ethanol oxidation in alkaline solution (ethanol oxidation specific activity of 6.54 mA cm(-2), only 2.14 mA cm(-2) for commercial Pd/C), high poison tolerance (i(f)/i(b) = 1.09), and excellent catalytic stability (only a loss of 4.3% of the initial ethanol oxidation reaction activity after 100 cycles). The superior performance of PdCu/PC can be ascribed to the abundant active reaction sites of porous carbon, uniform and good dispersion of PdCu nanoaolloys, as well as the strong metal-support interaction. This work is anticipated to be useful for the development of low-cost and highly active catalysts for fuel cells.