Shape selective reaction on crystallite particles is an important issue in catalytic reactions. In this investigation, Mn2O3 crystals with different shapes were prepared and tested in activation of peroxymonosulfate to produce sulfate radicals for degradation of aqueous phenol. The Mn2O3 shaped in cube, octahedra and truncated octahedra showed different activities in phenol degradation. Cubic Mn2O3 presented the highest activity among the three catalysts with an order of Mn2O3-cubic > Mn2O3-octahedra > Mn(2)O(3-)truncated, attributed to high surface area and surface atoms arrangement. In addition, kinetic studies showed that phenol degradation on Mn2O3-cubic follows first-order kinetics with activation energy of 61.2 kJ/mol. (c) 2014 Elsevier B.V. All rights reserved.