This paper describes a sonochemical approach for the synthesis of titanium dioxide nanospheres (TiO₂) decorated by palladium nanoparticles (Pd NPs). In this method, the TiO₂ nanospheres could be directly used as templates for the nucleation and growth of Pd NPs over their surface using PdCl₄^- as the Pd precursor, PVP as the stabilizer, ascorbic acid (AA) as the reducing agent, and water as the solvent. The Pd NPs presented uniform distribution over the TiO₂ nanospheres. Remarkably, the size of Pd NPs can be controlled by sequential reduction steps with adding excess of PdCl₄^-. The TEM images are well explained that controlled size of Pd NPs as shown in Fig. 1. The electrocatalytic activity of TiO₂-Pd electrode materials with size dependent Pd NPs was investigated towards the oxidation of ethanol and reduction of oxygen under alkaline medium. The results indicate that the nanocomposites materials are recognized to be an excellent electrocatalyst due to their excellent corrosion resistance and larger electrochemical active surface area.