Palladium compounds + p-benzoquinone (BQ) + molybdovanadophosphate are of great interest in many catalytic reactions. The electrochemical characteristics of the palladium acetate + BQ + molybdovanadophosphate system in acid aqueous solution are studied by cyclic voltammetry. The redox process of palladium species involves a two-electron reaction, which can be expressed as Pd(2+) + 2e <-> Pd(0). Since both BQ and molybdovanadophosphate can reoxidize Pd(0) to Pd(2+), an appropriate amount of BQ or molybdovanadophosphate can enhance the catalytic activity of Pd(2+) and the oxidative reaction rate. However, excessive BQ or molybdovanadophosphate decreases the reaction rate. Since molybdovanadophosphate can reoxidize the reduced form of BQ, adding an appropriate amount of molybdovanadophosphate to the Pd(2+) + BQ system enhances the catalytic activity of Pd(2+). The injection of oxygen to Pd(2+) + BQ + molybdovanadophosphate system can increase the oxidative reaction rate of molybdovanadophosphate and ultimately enhance the activity of Pd(2+).