Several novel kinds of bis-quaternary phosphonium salts of peroxotungstate and peroxomolybdate, such as Ph3P(CH2)(2)PPh3 [W(O-2)(4)](.)2H(2)O, Ph3P(CH2)(2)PPh3[WO(O-2)(2)(C2O4)](.)2H(2)O, Ph3P(CH2)(3)PPh3[W(O-2)(4)](.)2H(2)O, and Ph3P(CH2)(2)PPh3[MoO(O-2)(2)(C2O4)](.)2H(2)O, have been synthesized and characterized by elemental analysis, IR and Raman spectroscopy. Their catalytic properties in oxidation of cyclohexanol and benzyl alcohol to cyclohexanone, benzaldehyde or benzoic acid were investigated with aqueous 30% hydrogen peroxide under halide- and organic solvent-free conditions. The results show that the bis-quaternary phosphonium peroxotungstates have excellent catalytic ability to the oxidation reaction of benzyl alcohol and cyclohexanol by hydrogen peroxide. The Mo(IV) analog peroxo complexes were less active than peroxotungstates. The maximum yields of benzaldehyde, benzoic acid and cyclohexanone can be reached 93.89%, 88.87%, and 92.70%, respectively. (C) 2004 Elsevier B.V. All rights reserved.