Under mild conditions, monosubstituted benzyl alcohols were oxidized to benzaldehydes and benzoic acids in the presence of sodium 30-tungstopentaphosphate ( Preyssler's anion), [NaP5W30O120](14-), and hydrogen peroxide as an oxidant. This polyanion with high hydrolytic stability ( pH = 0 - 12), high thermal stability, and high acidic strength shows good activities. The effects of various parameters on the yield of the products, including a catalyst type, a nature of the substitutents, and temperature, were studied. Comparison between Keggin's heteropolyacids, H-3[PW12O40], H-3[PMo12O40], H-4[SiW12O40], and H-4[SiMo12O40], and Preyssler's anion shows that this polyanion reacts similar to Keggin's acids whitout any degradation of the structure.