Contrary to single counterparts, Pt-based bimetallic nanocrystals are attractive and feasible to decrease the cost, improve the catalytic activity and enhance the stability via morphology-, structure- and composition-engineering. Herein, porous dendritic alloyed Pt68Ag32 nanodandelions (NDs) were synthesized by a one-pot successive co-reduction method, using amrinone as the new stabilizer and structure director, without any template, seed or complicated instrument. The correlative shapes, composition, and crystalline structure were examined by a range of characterization techniques. It is found that the molar ratio of the precursors (AgNO3 and H2PtCl6), the dosage of amrinone, and different reductants play the essential roles during the synthesis process. The Pt68Ag32 NDs exhibited dramatically enlarged electrochemically active surface area, enhanced catalytic activity and stability for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) as compared to commercial Pt/C, Pt black, home-made Pt75Ag25 nanocrystals (NCs) and Pt56Ag44 NCs catalysts. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.