Many substituted anilines were converted into the corresponding azoxy benzenes as major products, by hydrogen peroxide, using Preyssler catalyst. The ability of various Preyssler catalysts as pure, H-14[NaP5W30O110], mixed addenda, H-14[NaP5W29MoO110], and cetylpyridinium acidic salt, was investigated. In all cases, the highest yield of azoxy compounds was observed, using H-14[NaP5W30O110] as catalyst. The oxidations of anilines with 30% H2O2 catalyzed by Preyssler catalysts in various solvents with different molar ratio of amine to oxidant, have been investigated and the results showed that the reaction yields were affected by changing the solvent as well as molar ratio of amine:oxidant. (c) 2006 Elsevier B.V. All rights reserved.