The catalytic performance of Pt-based nanocatalysts is closely related to the morphology and structure of the catalysts. We report herein the preparation of novel PtPd nanocatalysts with a hollow structure through a special galvanic replacement reaction and the high reaction selectivity of one kind of triblock pluronic copolymers. P123 (PEO₁₉-PPO₆₉-PEO₁₉) has unique selectivity for the reduction of K₂PdCl₄ and K₂PtCl₆. Relative to the commercial Pt/C and PtPd alloy catalysts, the PtPd nanocatalysts exhibited enhanced electrocatalytic activity toward methanol oxidation. The excellent electrocatalytic activity is due to the unique structure of PtPd nanocataysts.