Catalytic activity of a series of metalloporphyrin complexes in selective oxidation of cycloalkanes with molecular oxygen was investigated. The effects due to immobilization of these metallocomplexes on supports and their influences on the reaction course have been examined. Both, the type and the structure of the metallocomplexes as well as immobilization have been found to exert significant effect on the catalytic activity and selectivity. It has been demonstrated that the yields of oxidation products show an almost linear relationship with electronegativity of the axial ligands in the metalloporphyrin complexes. Extensive halogenation of the metalocomplex macrocycle enhances the catalytic activity of the metalloporphyrins. Parallel increase of the redox potential of metallocomplexes is observed showing a linear relationship with the number of the halogens on porphyrin macrocycle. Important conclusions concerning the reaction mechanism are advanced and the new reaction mechanism is discussed and proposed. (C) 2004 Elsevier B.V. All rights reserved.