A nanocomposite of polyaniline and silicomolybdate has been successfully co-deposited on electrode surface by aniline electropolymerization and the electrostatic interaction between the positive charge polyaniline and the negative charge silicomolybdate. The hybrid composite is found stable in various scan rate and different pH condition. The UV-Visible spectrum also shows no other interaction occurred in both the prepared solution and the hybrid film. Images study might provide that silicomolybdate covers over the polyaniline polymerized layer. Under 20 scan cycles, the average surface concentration (Γ) was estimated to be about 1.37×10-10 mol cm-2. Using the equation Ep = K – 2.303(RT/nF)logv and the two electrons transferred for polyaniline a charge transfer coefficient 0.60 was obtained. An apparent surface electron transfer rate constant (Ks) 1.878 s-1 was estimated for reversible redox peaks. This modified electrode maintains both electrocatalytic oxidation and reduction properties to AA, DA, EP, NEP, BrO3-, IO3-, NO2-, and S2O82-. Particularly, the electrocalysis is much better in strong acidic aqueous solution (pH 0.55). Applied potential of ER = 1.1 V (pH 1.5), the collection efficiency, N = IR/ID, was about 0.08.