Mn(III) and Mo(IV)-Salen complexes homogeneous and immobilized on a silica surface have been tested in the catalytic epoxidation of cyclooctene and cyclohexene with tert-butylhydroperoxide (TBHP) and hydrogen peroxide (HP) as an oxidant. The effects of reaction conditions on the epoxide yield as well as the epoxidation rate with different catalysts have been established. The catalytic decomposition of TBHP by manganese and molybdenum- Salen complexes has been studied. The peptide immobilized Salen complexes were compared in catalytic activity with ester bound ones. The munobilized catalysts show stable catalytic activity in manifold reuses. The Mo-Salen complexes homogeneous as well as immobilized exhibited high catalytic activity for the epoxidation of cyclooctene, whereas Mn-Salen complex systems cause additionally non-productive decomposition of hydroperoxide. (C) 2007 Elsevier B.V. All rights reserved.