Alanine-salicylaldehyde Schiff base Mn(III) complex was entrapped into SiO2 matrix by direct physical encapsulation and copolymerization of the functionally modified complex and tetraethoxysilane. The two heterogenized catalysts were characterized by Fr-IR, XPS, N-2 adsorption and 1CP. and their catalytic performance in the aerobic epoxidation of cyclohexene was investigated. The experimental results showed both that the catalysts had higher catalytic activity and better epoxide selectivity than the homogeneous catalyst. After six recycle runs, the anchored catalyst had 1.6% activity reduction while that of the physically encapsulated one was 12.1 %. ICP analysis indicated that complex leaching took place for the physically encapsulated catalyst but no complex leaching was found for the anchored one. Thus, for the aerobic epoxiclation of cyclohexene (2.5 ml) catalyzed by the anchored catalyst (0.01 mmol) in the presence of isobutraldehyde (isobutraldehyde:cyclohexene = 2: 1) using acetonitrile (60 ml) as solvent at 35 C-circle for 6 h the conversion reached 99.6% with a selectivity of 88.2%. This catalyst can be reused by simple filtration up to six times, retaining 99.4% of the activity of the fresh catalyst. (c) 2005 Elsevier B.V. All rights reserved.