In this work, we report a concise method to self-assemble Pd nanoparticles onto the Surface of MWNTs. Highly dispersed palladium nanoparticles are loaded on the MWNTs functionalized with mercaptobenzene moieties. The structure of the resulting Pd-fMWNT composite were characterized by transmission electron microscopy (TEM), the results show that the chemically synthesized Pd nanoparticles were homogeneously dispersed and well-separated from one another on the functional MWNT surfaces. Cyclic voltammogram (CV) showed that Pd-fMWNT composite materials perform excellent electrocatalytic activity and long-term stability toward formaldehyde oxidation. Electrochemical impedance spectroscopy (EIS) revealed the strong interaction between fMWNTs and I'd facilitates the effective degree of electron dolocalization, and thus enhances the conductivity of the composite. The results imply that the self-organized Pd-fMWNT composite as a promising support material shows the excellent electrocatalytic activity and has a promising application potential in fuel cells and biosensors. (c) 2008 Elsevier B.V. All rights reserved.