The highly dispersed and ultrafine carbon supported Pd nanoparticles (Pd/C) catalyst was synthesized by NaBH4 reduction method in the presence of ethylenediamine-tetramethylene phosphonic acid (EDTMP) ligand. The formation of the ultrafine Pd nanoparticles can be attributed to the avoidance of Pd(OH)(2) precipitation and the decrease in the reduction potential of Pd-II species in EDTMP-Pd-II complex during the preparation of Pd/C catalyst. Electrochemical measurements indicated the resulting Pd/C catalyst possessed a significant electrocatalytic performance for hydrazine oxidation under the strong acidic conditions, indicating that the Pd/C catalyst has potential application in fabrication of acidic direct hydrazine fuel cell. (c) 2011 Elsevier B.V. All rights reserved.