Abstract. Mesoporous silica-supported chiral Mn(salen) catalysts were prepared and evaluated in the heterogeneous asymmetric epoxidation of β-methylstyrene with NaClO as an oxidant. Homogeneous and immobilized Mn(salen) catalysts exhibit similar cis/trans ratios and ee values when trans-substrate is used but different cis/trans ratios and ee values when cis-substrate is used. The productio…