Transition-metal (TM) species (Mn, V, and Cr) were incorporated by an anion-exchange method into MCM-48, The TM-MCM-48 materials were characterized by XRD, HRTEM, N-2 adsorption-desorption. ESR, Raman, and NH3-TPD. The structural and textural properties of the materials are discussed, as is the nature of the TM species introduced in the mesoporous host, The catalytic activity and selectivity of the TM-MCM-48 in the oxidation of styrene with TBHP as an oxidant agent are explored. All of the catalysts produce benzaldehyde and styrene oxide as the main products. Mn-MCM-48 showed the highest selectivity for styrene oxide, but with a maximum conversion of 59%. V-MCM-48 shows the highest conversion of styrene (100%) and the highest selectivity (88%) for benzaldehyde, The Cr catalyst shows the poorest performance in terms of selectivity. The TM-MCM-48 catalysts are very active in the oxidation of styrene. and their activity depends on the nature of the transition metal used. (c) 2005 Elsevier Inc. All rights reserved.