The catalytic reactions of M(TPP)Cl (M = Fe ( 1), Mn ( 2)), Fe(TMP)Cl ( 3), and Fe(TDCPP)Cl ( 4) (H 2TPP = 5,10,15,20-tetraphenylporphyrin; H 2TMP = 5,10,15,20-tetramesitylporphyrin; H 2TDCPP = 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin) with 2,4-diaminotoluene ( 5) and p-phenylenediamine ( 6) were carried out using t-BuOOH (3 M isooctane solution) as oxidant. With the former substrate, the nitro derivatives 2-amino-4-nitrotoluene ( 5a) and 2,4-dinitrotoluene ( 5b) (total yield of 5a + 5b ranges between 27–55%) were obtained with low yields and their amounts depend on the catalyst used. An other oxidation product of 5 was 3-amino-4( tert-butyldioxy)-4-methyl-2,5-cyclohexadien-1-imine hydrochloride ( 5c) (20%). In the oxidation reaction of 6, 4-nitroaniline ( 6a) (11%) was obtained only with catalyst 1, being an unidentified black solid ( 6b) the major oxidation product. 6b was always the main product with all the studied catalysts ( 1–3), while the yields and nature of the recovered azobenzenes depend on the metalloporphyrin used: the highest yield of 4,4′-dinitroazobenzene ( 6c) (37%) was obtained with 3 in the presence of acetic acid, 4,4′-diaminoazobenzene ( 6d) (19%) was obtained with 4, and 4-amino,4′-nitroazobenzene ( 6e) (17%) with 3. The catalytic reactions of Mo(O)(O 2) 2(H 2O)(HMPA) ( 7) (HMPA = hexamethylphosphotriamide), with 5, 6, and 4-aminodiphenylamine ( 8), in the presence of H 2O 2 (35% w/w water solution) as oxidant, were studied. The corresponding mononitro derivatives, 5a, 6a, and 4-nitrodiphenylamine ( 8a) were obtained with fair selectivity (35, 70, and 60%, respectively).