Rare earth metal sandwiched Keggin-type heteropolyoxometalates, K-11[RE(PW11O39)(2)] (RE-PW11, RE = La, Ce, Pr, Nd, Sm, Eu, Dy and Y), were anchored onto aminosilylated mesoporous silica SBA-15 and the resulting RE-PW11/APTS/SBA-15 materials were characterized by ICP, FT-IR, XRD, N-2 adsorption, (31)p MAS NMR and TEM. The RE-PW11 clusters preserve their structure in the surface-modified mesopores. The catalytic activity of RE-PW11 clusters was tested on heterogeneous oxidation of cyclohexene by H2O2. The interaction between RE-PW11 and amino groups grafted on the channel surface of SBA-15 leads to strong immobilization of RE-PW11 due to the introduction of the rare earth metal centre, which is against the leaching during the reaction. (C) 2007 Elsevier B.V. All rights reserved.