The synthesis, characterization, and application of bimetallic Pd-Pt nanocatalysts with heterogeneous structures are reported. The Pd tetrapod core is demonstrated to enhance the catalytic activity and durability of Pd@Pt nanodendrites for the oxygen reduction reaction (ORR). Special attention is given to the effects of oxalate-ion-formaldehyde during the hydrothermal synthesis of various Pd morphologies at different temperatures. Pd tetrapod synthesis can be delicately achieved without directly using hazardous CO gas. 30 wt% Pt on tetrapodal and truncated-octahedral Pd cores and 50 wt% Pt on tetrapodal Pd cores are prepared and compared against the commercial Pt/C catalyst (E-Tek) for ORR. The Pdtetrapod@30 wt% Pt catalyst exhibits the highest ORR activity. Overall, the Pd tetrapod core is a functional morphology which offers high-index facets for the subsequent deposition of Pt(110) nanodendrites, with the bimetallic interaction between two materials allowing for good electron transfer from the Pd core onto the Pt surfaces. Both effects contribute to the increased catalytic activity of Pd tetrapod@30 wt% Pt, even under a lower loading of Pt. Furthermore, Pdtetrapod@30 wt% Pt has a rather large particle size (?39.5 nm) which enhances durability and resistance to the agglomeration of Pt. Copyright 2013 Elsevier B.V. All rights reserved.