Palladium nanoparticles (Pd-NPs)/polyaniline (PAni)/titanium (Ti) catalysts were prepared using electroless deposition of Pd-NPs on PAni matrixes coated on Ti substrate. PAni/Ti electrodes were synthesized by electro-polymerization of aniline on Ti. The morphology of Pd-NPs on PAni/Ti electrodes were characterized by scanning electron microscopy technique and results indicated that Pd-NPs were uniformly dispersed on the surface of PAni film. The electro-catalytic properties of Pd-NPs/PAni/Ti catalysts toward oxidation of hydrazine were investigated by different electrochemical methods and results showed that Pd-NPs/PAni/Ti catalysts have high electrochemical activity. In addition, the mechanism of hydrazine electrochemical oxidation catalyzed by Pd-NPs/PAni/Ti was investigated. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011