We report the synthesis of a series of praseodymium oxide/polypyrrole (Pr(6)O(11)/PPy) nanocomposites, and their application in the electrochemical energy storage. The Pr(6)O(11)/PPy nanocomposites were synthesized by the in situ surface-initiated polymerization technique based on the amine-functionalized Pr(6)O(11) nanoparticles. The nanocomposites exhibit the well-defined core/shell structure observed by transmission electron microscopy (TEM) and scanning electron microscope (SEM). Thermogravimetric analysis reveals a significantly enhanced thermal stability with the addition of the amine-functionalized Pr(6)O(11) nanoparticles. Furthermore, they possess weak temperature dependence of the conductivity and the highest specific capacitance of 400 Fg(-1) at the charge-discharge current density of 10 mA cm(-2) in 1.0 M NaNO(3) electrolyte solution when being used as the electrode material for supercapacitor. (C) 2011 Elsevier Ltd. All rights reserved.