Three types of magnetic polymer nanospheres immobilizing Mn(III) porphyrins appending p-OCH3, p-H and p-Cl phenyl substituents (designated as MPNSs(MnMP), MPNSs(MnPP) and MPNSs(MnCP), respectively) were synthesized and their catalytic activities as biomimetic catalysts to hydroxylate cyclohexane with molecular oxygen were investigated. The catalytic efficiencies of these magnetic nanospheres are much higher than those of the non-supported Mn(III) porphyrin analogues and follow the order of MPNSs(MnMP) > MPNSs(MnPP) > MPNSs(MnCP). It is also found that these nanospheres have good magnetic responsiveness and thus can be completely recovered by applying an external magnetic field. Furthermore, they can maintain their catalytic activities after being recycled several times. These results may be helpful in designing new, highly efficient metalloporphyrin catalysts. (C) 2008 Elsevier B.V. All rights reserved.