In this work, well-defined dendritic Pt-Au core shell alloy nanocrystals (Pt-Au CSANCs) are synthesized on a large scale via a simple one-pot oligonucleotide-assisted successive coreduction route. The atomic ratios of Pt to Au in the core and shell of Pt Au CSANCs are 4:1 and 2:3, respectively. Polyinosinic acid (PIA), a commercially available oligonucleotide, is employed as a capping agent. Control experiments demonstrate that the dosage of PIA and the successive coreduction are essential to form dendritic Pt Au CSANCs. The as-synthesized architectures show enhanced electrocatalytic activity and improved stability for methanol oxidation in alkaline media by comparison with PtAu nanocrystals and commercial Pt black catalysts: (C) 2015 Elsevier B.V. All rights reserved.