The metal-organic framework (MOF) MIL-101Cr was readily encapsulated by a very thin shell (around 30 nm) of hydrophobic mesoporous silica, which replicates the irregular shape of the MOF nanocrystals. Such a silica shell facilitates the diffusion of hydrophobic reactants with enhancement of the catalytic activity of the MOF and significantly improved catalytic stability of the MOF in the oxidation of indene.