Mesoporous alpha-MnO2 and its supported Co(3)O4 nanoparticles were synthesized, characterized and tested in heterogeneous activation of peroxymonosulfate (PMS) for phenol degradation in aqueous solution. alpha-MnO2 supported Co3O4 presented as nanorod particles and showed H-2 redox reduction at low temperature. Bulk alpha-MnO2 and Co3O4 could activate peroxymonosulfate to generate sulfate radicals for phenol degradation but at low activity. Co3O4/MnO2 nanoparticles exhibited much high activity in peroxymonosulfate activation for phenol degradation with 100% conversion in 20 min and 3 wt% is the optimum Co loading. Phenol degradation followed a first order kinetics. Stability tests also showed that Co3O4/MnO2 presented stable performance in phenol degradation in several runs. (C) 2012 Elsevier B.V. All rights reserved.