MCPA has been purified by crystallization and its purity for phenol and chlorocresol, present as contaminants of the commercial material, was checked by HPLC. The purified MCPA was used in the chemical reactivity with two catalytic systems manganese(III)tetraphenylporphyrinate-iodosylbenzene and bis[salycilideneethylenediiminocobalt(II)]-dioxygen. The reaction products were studied.