The reaction of 4-aminotoluene with ozone in acetic acid was studied. It was found that the reaction proceeds at a high rate, giving predominantly tars. The product composition changes after acylation of the amino group: aliphatic peroxides prevailed among the oxidation products and 4-acetylaminobenzoic acid was identified (16%) as well. It was shown that the presence of a catalyst (cobalt(II) acetate) had no substantial effect on the oxidation selectivity for the methyl group (32%) and only the addition of potassium bromide increased the activity of the catalyst; the yield of 4-acetylaminobenzoic acid reached 70%. The mechanism of oxidation in the presence of a cobalt-bromide catalyst explaining the obtained results was discussed.