The immobilization of copperperchlorophthalocyanine (CUCl16PC) complex in the channels of HSi-MCM-41 molecular sieves has been carried out by (i) post-synthesis in the presence of 3-aminopropyltriethoxysilane (3-APTES) and (ii) impregnation in the absence of 3-APTES. The resulting host-guest samples were characterized by XRD, MAS-NMR, nitrogen adsorption, IR and cyclic voltammetry. Each sample showed an IR band at 1390cm(-1) suggesting the presence Of CUCl16PC complex in the channels of HSi-MCM-41. The results of the alkene epoxidation in presence of (i) TBHP and (ii) O-2/isobutyraidehyde are compared. The oxo-metal and acyl peroxy radical species that formed predominantly using isobutyraldehyde give a high yield of epoxide, as compared to the reaction using TBHP as the oxidant. (C) 2003 Elsevier B.V. All rights reserved.