A kind of inorganic-organic hybrid polyoxometalate (POM) nanoparticle [(CH3)(4)N](6)P2Mo18O62.9H(2)o has been designed and prepared by solid-state reaction at room temperature and immobilized on the surface of a wax impregnated graphite electrode (WIGE) by the sol-gel technique for the first time. The electrochemical behavior of the [(CH3)(4)N](6)P2Mo18O62.9H(2)O nanoparticle modified WIGE (P2Mo18-WIGE) has been studied in detail, including pH-dependence, solvent effect and stability. The electrocatalytic behavior of the P2Mo18-WIGE toward the reduction of chlorate, hydrogen peroxide and nitrite in 1 M H2SO4 aqueous solution is reported. The experimental results show that the P2Mo18-WIGE not only maintains the electrochemical activity and electrocatalytic properties of the H6P2Mo18O62, but also shows remarkable stability due to insolubility of the hybrid POM nanoparticles. which is important for practical applications. The significance of our research work is to provide a kind of novel and very stable POM-based solid nano-material applied in electrode modification.