Silica-supported molybdenum surface complexes were prepared by the reaction between (N)Mo(OtBu)₃ and silica via displacement of the tert-butoxy ligands for siloxyls from the silica surface. The structure of the surface molybdenum complexes was well defined by in-situ FT-IR, elemental analysis, ¹H NMR and ¹³C CP/MAS NMR techniques. The surface complexes could undergo alcoholysis reaction with CD₃OD and CH₃OH in the same way as free (N)Mo(OtBu)₃ and they show high catalytic activity and selectivity in olefin epoxidation. Initial rates up to 24.9 mmol epoxide (mmol Mo)⁻¹ min⁻¹ were achieved in the epoxidation of cyclohexene using TBHP as oxidant.