A cerium(IV)-containing mesoporous silica, Ce-TUD-1, has been synthesized using the sol-gel technique, where a Ce(IV) acetyl acetonate complex was used as the Ce(IV) precursor. The material proved to be an active catalyst for both the oxidation of p-tert-butyl toluene to p-tert-butyl benzaldehyde and the peroxidative halogenation of Phenol Red. Both reactions require the presence of bromide ions. The conversion of p-tert-butyl toluene over Ce-TUD-1, using 30 wt % aqueous hydrogen peroxide as the oxidant and potassium bromide as the co-catalyst, was 37%, somewhat higher than soluble Ce(III) and Ce(IV) salts. The aldehyde selectivity of 57% was comparable to that of both cerium salts. Regeneration experiments showed that the catalytic activity is slightly reduced in a subsequent run (90% compared to the first run). In the Phenol Red halogenation reaction, it is proposed that Ce-TUD-1 catalyzes the bromination via a pathway mechanistically distinct from well-known V, W, or Ti catalysts, which involve metal-peroxo intermediates. Ce(IV) is thought to act as a one-electron oxidant, reacting with bromide ions to yield bromine radicals, which then react with the organic substrate to give Phenol Red radicals. Reaction of hydrogen peroxide with bromide ions, in turn, yields bromine (Br-2), which is proposed to react with the organic radical to give the brominated product.