Novel urchin-like Pd nanostructures were firstly synthesized using a simple replacement reaction between Al and PdCl2 aqueous solution at room temperature without the assistance of any surfactant or ligand. Their phase structure, morphology, specific surface area, and catalytic property were characterized by XRD, TEM, EDS, BET and DSC/TG. The results show numerous one-dimensional Pd nanorods radiate from the center of the aluminum templates to form an urchin-like shape with a diameter of similar to 0.5-1.0 mu m. The as-prepared urchin-like Pd nanostructures can serve as a promising additive to accelerate the thermal decomposition of ammonium perchlorate (AP), a key oxidizer in composite solid propellants. (C) 2011 Elsevier B.V. All rights reserved.